diff --git a/HW4/ParenthesesBalance/src/main.c b/HW4/ParenthesesBalance/src/main.c
new file mode 100644
index 0000000..fe09a85
--- /dev/null
+++ b/HW4/ParenthesesBalance/src/main.c
@@ -0,0 +1,56 @@
+#include "../../modules/stack/stack.h"
+#include <stdbool.h>
+#include <stdio.h>
+
+bool checkParenthesesBalance(const char *checkString);
+
+int main() {
+    bool result = checkParenthesesBalance("(Hello!)(");
+    printf("%d\n", result);
+
+    result = checkParenthesesBalance(")/-l,,.s3");
+    printf("%d\n", result);
+
+    result = checkParenthesesBalance("({[]})asd()");
+    printf("%d\n", result);
+
+    result = checkParenthesesBalance("([{]})");
+    printf("%d\n", result);
+}
+
+bool checkParenthesesBalance(const char *checkString) {
+    if (checkString == NULL)
+        return true;
+
+    Stack *head = NULL;
+    int errorCode = 0;
+
+    for (int i = 0; checkString[i] != '\0'; ++i) {
+        if (checkString[i] == '(' || checkString[i] == '[' ||
+            checkString[i] == '{') {
+            errorCode = pushToStack(checkString[i], &head);
+            if (errorCode == -1) {
+                printf("Error: couldn't allocate memory\n");
+                freeStack(head);
+                return false;
+            }
+        } else if (checkString[i] == ')' || checkString[i] == ']' ||
+                   checkString[i] == '}') {
+            if (head != NULL) {
+                char lastParenthesis = popFromStack(&head);
+                if ((checkString[i] == ')' && lastParenthesis != '(') ||
+                    (checkString[i] == ']' && lastParenthesis != '[') ||
+                    (checkString[i] == '}' && lastParenthesis != '{')) {
+                    freeStack(head);
+                    return false;
+                }
+            } else
+                return false;
+        }
+    }
+
+    bool isBalanced = (head == NULL);
+    freeStack(head);
+    return isBalanced;
+}
+
diff --git a/HW4/modules/queue/queue.c b/HW4/modules/queue/queue.c
new file mode 100644
index 0000000..f1603aa
--- /dev/null
+++ b/HW4/modules/queue/queue.c
@@ -0,0 +1,39 @@
+#include "queue.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+int pushToQueue(char data, Queue **head, Queue **tail) {
+    Queue *newQueueNode = (Queue *)malloc(sizeof(Queue));
+    if (newQueueNode == NULL)
+        return -1;
+
+    newQueueNode->data = data;
+    newQueueNode->next = NULL;
+
+    if (*head == NULL) {
+        *head = newQueueNode;
+        *tail = newQueueNode;
+    } else {
+        (*tail)->next = newQueueNode;
+        *tail = newQueueNode;
+    }
+    return 0;
+}
+
+void printQueue(Queue *head) {
+    while (head != NULL) {
+        printf("%c ", head->data);
+        head = head->next;
+    }
+    printf("\n");
+}
+
+void freeQueue(Queue *head) {
+    Queue *current = head;
+    while (current != NULL) {
+        Queue *next = current->next;
+        free(current);
+        current = next;
+    }
+}
+
diff --git a/HW4/modules/queue/queue.h b/HW4/modules/queue/queue.h
new file mode 100644
index 0000000..b63f5e2
--- /dev/null
+++ b/HW4/modules/queue/queue.h
@@ -0,0 +1,28 @@
+#pragma once
+
+typedef struct Queue {
+    char data;
+    struct Queue *next;
+} Queue;
+
+/**
+ * @brief Push element to queue
+ * @param data Character to push
+ * @param head Pointer to pointer of queue head
+ * @param tail Pointer to pointer of queue tail
+ * @return -1 if couldn't allocate memory, 0 otherwise
+ */
+int pushToQueue(char data, Queue **head, Queue **tail);
+
+/**
+ * @brief Print all elements in queue
+ * @param head Pointer to queue head
+ */
+void printQueue(Queue *head);
+
+/**
+ * @brief Free all queue memory
+ * @param head Pointer to queue head
+ */
+void freeQueue(Queue *head);
+
diff --git a/HW4/modules/stack/stack.c b/HW4/modules/stack/stack.c
new file mode 100644
index 0000000..ac95e12
--- /dev/null
+++ b/HW4/modules/stack/stack.c
@@ -0,0 +1,37 @@
+#include "stack.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+int pushToStack(char data, Stack **head) {
+    Stack *newNode =
+        (Stack *)malloc(sizeof(Stack));
+    if (newNode == NULL)
+        return -1;
+    else {
+        newNode->data = data;
+        newNode->next = *head;
+        *head = newNode;
+        return 0;
+    }
+}
+
+char popFromStack(Stack **head) {
+    if (*head == NULL)
+        return '\0';
+
+    Stack *lastNode = *head;
+    char lastNodeData = lastNode->data;
+    *head = (*head)->next;
+    free(lastNode);
+    return lastNodeData;
+}
+
+void freeStack(Stack *head) {
+    Stack *current = head;
+    while (current != NULL) {
+        Stack *next = current->next;
+        free(current);
+        current = next;
+    }
+}
+
diff --git a/HW4/modules/stack/stack.h b/HW4/modules/stack/stack.h
new file mode 100644
index 0000000..516ce3c
--- /dev/null
+++ b/HW4/modules/stack/stack.h
@@ -0,0 +1,28 @@
+#pragma once
+
+typedef struct Stack {
+    char data;
+    struct Stack *next;
+} Stack;
+
+/**
+ * @brief Push element to stack
+ * @param data Character to push
+ * @param head Pointer to pointer of stack head
+ * @return -1 if couldn't allocate memory, 0 otherwise
+ */
+int pushToStack(char data, Stack **head);
+
+/**
+ * @brief Pop element from stack
+ * @param head Pointer to pointer of stack head
+ * @return Popped character or '\0' if stack is empty
+ */
+char popFromStack(Stack **head);
+
+/**
+ * @brief Free all stack memory
+ * @param head Pointer to stack head
+ */
+void freeStack(Stack *head);
+