diff --git a/src/storage/SimpleLRU.cpp b/src/storage/SimpleLRU.cpp
index 0b895bcdf..db1e8672d 100644
--- a/src/storage/SimpleLRU.cpp
+++ b/src/storage/SimpleLRU.cpp
@@ -1,22 +1,180 @@
 #include "SimpleLRU.h"
+#include "iostream"
 
 namespace Afina {
 namespace Backend {
 
+void SimpleLRU::LRU_delete() {
+	lru_node* deleted_node = _lru_tail;
+	_curr_size -= deleted_node->key.size() + deleted_node->value.size();
+	_lru_index.erase(deleted_node->key);
+	if (deleted_node != _lru_head.get())
+	{
+		_lru_tail = deleted_node->prev;
+		_lru_tail->next.reset();
+	}
+	else //there is only one element in list
+	{
+		_lru_head.reset();
+	}
+}
+
+void SimpleLRU::LRU_move(lru_node* moved_node) {
+	if (_lru_head.get() == moved_node) //node is already a head
+	{
+		return;
+	}
+	if (!moved_node->next.get()) //move the last node
+	{
+		_lru_tail = moved_node->prev;
+		_lru_head.get()->prev = moved_node;
+		moved_node->next = std::move(_lru_head);
+		_lru_head = std::move(moved_node->prev->next);
+	}
+	else
+	{
+		auto p = std::move(_lru_head);
+		_lru_head = std::move(moved_node->prev->next);
+		moved_node->prev->next = std::move(moved_node->next);
+		p.get()->prev = moved_node;
+		moved_node->next = std::move(p);
+		moved_node->prev->next->prev = moved_node->prev;
+	}
+}
+
+void SimpleLRU::PutIn(const std::string &key, const std::string &value, std::size_t node_size) {
+	while (node_size + _curr_size > _max_size)
+	{
+		LRU_delete();
+	}
+	lru_node *new_node = new lru_node{key, value, nullptr, nullptr};
+	//insert
+	if (_lru_head.get())
+	{
+		_lru_head.get()->prev = new_node;
+	}
+	else
+	{
+		_lru_tail = new_node;
+	}
+	new_node->prev = nullptr;
+	new_node->next = std::move(_lru_head);
+	_lru_head.reset(new_node);
+	//end of insert
+	_lru_index.insert({std::reference_wrapper<const std::string>(new_node->key), std::reference_wrapper<lru_node>(*new_node)});
+	_curr_size += node_size;
+}
+
+void SimpleLRU::SetIn(lru_node &node, const std::string &value) {
+	int diff_size = value.size() - node.value.size(); //change size_t on int
+	LRU_move(&node);
+	while (_curr_size + diff_size > _max_size)
+	{
+		LRU_delete();
+	}
+	node.value = value;
+	_curr_size += diff_size;
+}
+
 // See MapBasedGlobalLockImpl.h
-bool SimpleLRU::Put(const std::string &key, const std::string &value) { return false; }
+bool SimpleLRU::Put(const std::string &key, const std::string &value) {
+	std::size_t node_size = key.size() + value.size();
+	if (node_size > _max_size) // can't guarantee invariant
+	{
+		return false;
+	}
+	auto node = _lru_index.find(key);
+	
+	if (node ==  _lru_index.end()) // there is no key
+	{
+		PutIn(key, value, node_size);
+	}
+	else
+	{
+		SetIn((node->second).get(), value);
+	}
+	return true; 
+}
 
 // See MapBasedGlobalLockImpl.h
-bool SimpleLRU::PutIfAbsent(const std::string &key, const std::string &value) { return false; }
+bool SimpleLRU::PutIfAbsent(const std::string &key, const std::string &value) { 
+	std::size_t node_size = key.size() + value.size();
+	if (node_size > _max_size) // can't guarantee invariant
+	{
+		return false;
+	}
+	auto node = _lru_index.find(key);
+	if (node ==  _lru_index.end()) // there is no key
+	{
+		PutIn(key, value, node_size);
+		return true;
+	}
+	return false; 
+}
 
 // See MapBasedGlobalLockImpl.h
-bool SimpleLRU::Set(const std::string &key, const std::string &value) { return false; }
+bool SimpleLRU::Set(const std::string &key, const std::string &value) { 
+	int node_size = key.size() + value.size();
+	if (node_size > _max_size) // can't guarantee invariant
+	{
+		return false;
+	}
+	auto node = _lru_index.find(key);
+	if (node !=  _lru_index.end()) // key exists
+	{
+		SetIn((node->second).get(), value);
+		return true; 
+	}
+	return false;
+}
 
 // See MapBasedGlobalLockImpl.h
-bool SimpleLRU::Delete(const std::string &key) { return false; }
+bool SimpleLRU::Delete(const std::string &key) { 
+	auto p = _lru_index.find(key);
+	if (p == _lru_index.end())
+	{
+		return false;
+	}
+	lru_node* node = &(p->second.get());
+	_lru_index.erase(p);
+	_curr_size -= node->key.size() + node->value.size();
+	if (node == _lru_head.get()) //deleting head
+	{
+		if (!node->next.get()) //one element in list
+		{
+			_lru_tail = nullptr;
+			_lru_head.reset();
+		}
+		else
+		{
+			node->next.get()->prev = nullptr;
+			_lru_head = std::move(node->next);
+		}
+	}
+	else if (!node->next.get()) //deleting last element
+	{
+		_lru_tail = node->prev;
+		node->prev->next.reset();
+	}
+	else
+	{
+		node->next.get()->prev = node->prev;
+		node->prev->next = std::move(node->next);
+	}
+	return true; 
+}
 
 // See MapBasedGlobalLockImpl.h
-bool SimpleLRU::Get(const std::string &key, std::string &value) { return false; }
+bool SimpleLRU::Get(const std::string &key, std::string &value) {
+	auto node = _lru_index.find(key);
+	if (node !=  _lru_index.end())
+	{
+		value = node->second.get().value;
+		LRU_move(&node->second.get());
+		return true;
+	}
+	return false; 
+}
 
 } // namespace Backend
 } // namespace Afina
diff --git a/src/storage/SimpleLRU.h b/src/storage/SimpleLRU.h
index 6e05435a8..4fc68622d 100644
--- a/src/storage/SimpleLRU.h
+++ b/src/storage/SimpleLRU.h
@@ -17,49 +17,62 @@ namespace Backend {
  */
 class SimpleLRU : public Afina::Storage {
 public:
-    SimpleLRU(size_t max_size = 1024) : _max_size(max_size) {}
+	SimpleLRU(size_t max_size = 1024) : _max_size(max_size), _curr_size(0), _lru_tail(nullptr) {}
 
-    ~SimpleLRU() {
-        _lru_index.clear();
-        _lru_head.reset(); // TODO: Here is stack overflow
-    }
+	~SimpleLRU() {
+		_lru_index.clear();
+		while ((_lru_tail != nullptr) && (_lru_tail != _lru_head.get()))
+		{
+			_lru_tail = _lru_tail->prev;
+			_lru_tail->next.reset();
+		}
+		_lru_head.reset();
+	}
 
-    // Implements Afina::Storage interface
-    bool Put(const std::string &key, const std::string &value) override;
+	// Implements Afina::Storage interface
+	bool Put(const std::string &key, const std::string &value) override;
 
-    // Implements Afina::Storage interface
-    bool PutIfAbsent(const std::string &key, const std::string &value) override;
+	// Implements Afina::Storage interface
+	bool PutIfAbsent(const std::string &key, const std::string &value) override;
 
-    // Implements Afina::Storage interface
-    bool Set(const std::string &key, const std::string &value) override;
+	// Implements Afina::Storage interface
+	bool Set(const std::string &key, const std::string &value) override;
 
-    // Implements Afina::Storage interface
-    bool Delete(const std::string &key) override;
+	// Implements Afina::Storage interface
+	bool Delete(const std::string &key) override;
 
-    // Implements Afina::Storage interface
-    bool Get(const std::string &key, std::string &value) override;
+	// Implements Afina::Storage interface
+	bool Get(const std::string &key, std::string &value) override;
 
 private:
-    // LRU cache node
-    using lru_node = struct lru_node {
-        std::string key;
-        std::string value;
-        std::unique_ptr<lru_node> prev;
-        std::unique_ptr<lru_node> next;
-    };
-
-    // Maximum number of bytes could be stored in this cache.
-    // i.e all (keys+values) must be less the _max_size
-    std::size_t _max_size;
-
-    // Main storage of lru_nodes, elements in this list ordered descending by "freshness": in the head
-    // element that wasn't used for longest time.
-    //
-    // List owns all nodes
-    std::unique_ptr<lru_node> _lru_head;
-
-    // Index of nodes from list above, allows fast random access to elements by lru_node#key
-    std::map<std::reference_wrapper<std::string>, std::reference_wrapper<lru_node>, std::less<std::string>> _lru_index;
+	// LRU cache node
+	using lru_node = struct lru_node {
+		const std::string key;
+		std::string value;
+		lru_node* prev;
+		std::unique_ptr<lru_node> next;
+	};
+
+	// Maximum number of bytes could be stored in this cache.
+	// i.e all (keys+values) must be less the _max_size
+	const std::size_t _max_size;
+	std::size_t _curr_size;
+
+	// Main storage of lru_nodes, elements in this list ordered descending by "freshness": in the head
+	// element that wasn't used for longest time.
+	//
+	// List owns all nodes
+	std::unique_ptr<lru_node> _lru_head;
+	lru_node* _lru_tail;
+
+	// Index of nodes from list above, allows fast random access to elements by lru_node#key
+	std::map<std::reference_wrapper<const std::string>, std::reference_wrapper<lru_node>, std::less<std::string>> _lru_index;
+
+	//help functions
+	void LRU_delete();
+	void LRU_move(lru_node* moved_node);
+	void PutIn(const std::string &key, const std::string &value, std::size_t node_size);
+	void SetIn(lru_node &node, const std::string &value);
 };
 
 } // namespace Backend
diff --git a/test/storage/StorageTest.cpp b/test/storage/StorageTest.cpp
index b3fae8d37..0717bc49e 100644
--- a/test/storage/StorageTest.cpp
+++ b/test/storage/StorageTest.cpp
@@ -195,3 +195,14 @@ TEST(StorageTest, MaxTest) {
         EXPECT_FALSE(storage.Get(key, res));
     }
 }
+
+TEST(StorageTest, SHORT_NEW_VALUE){
+	SimpleLRU storage(22);
+	std::string result;
+	EXPECT_TRUE(storage.Put("KEY", "VERY_VERY_BIG_VALUE"));
+	EXPECT_TRUE(storage.Put("KEY1", "VALUE"));
+	EXPECT_TRUE(storage.Put("KEY2", "VALUE"));
+	EXPECT_TRUE(storage.Put("KEY", "VALUE"));
+	EXPECT_TRUE(storage.Get("KEY", result));
+	EXPECT_TRUE(storage.Get("KEY2", result));
+}