diff --git a/HW4/ShuntingYard/src/main.c b/HW4/ShuntingYard/src/main.c
new file mode 100644
index 0000000..5b66dcd
--- /dev/null
+++ b/HW4/ShuntingYard/src/main.c
@@ -0,0 +1,130 @@
+#include "../../modules/queue/queue.h"
+#include "../../modules/stack/stack.h"
+#include <ctype.h>
+#include <stdio.h>
+
+void shuntingYard(const char *expression);
+int getPrecedence(char operation);
+
+int main() {
+    shuntingYard("1 + 1");
+    shuntingYard("(1 + 1) * 2");
+    shuntingYard("1 + 1 * 2");
+    shuntingYard("3 + 4 * 2 / (1 - 5)");
+    shuntingYard("1 + 2 + (3 + 4)");
+    return 0;
+}
+
+void shuntingYard(const char *expression) {
+    Stack *stackHead = NULL;
+    Queue *queueHead = NULL;
+    Queue *queueTail = NULL;
+    int errorCode = 0;
+
+    for (int i = 0; expression[i] != '\0'; ++i) {
+        char currChar = expression[i];
+
+        if (isdigit(currChar)) {
+            errorCode = pushToQueue(currChar, &queueHead, &queueTail);
+            if (errorCode == -1) {
+                printf("Error: couldn't allocate memory\n");
+                freeQueue(queueHead);
+                freeStack(stackHead);
+                return;
+            }
+        } else if (currChar == '+' || currChar == '-' || currChar == '*' ||
+                   currChar == '/') {
+            while (stackHead != NULL &&
+                   getPrecedence(currChar) <= getPrecedence(stackHead->data)) {
+                char lastStackOp = popFromStack(&stackHead);
+                if (lastStackOp == '\0') {
+                    printf("Error: trying to put empty operation into queue\n");
+                    freeQueue(queueHead);
+                    freeStack(stackHead);
+                    return;
+                }
+                errorCode = pushToQueue(lastStackOp, &queueHead, &queueTail);
+                if (errorCode == -1) {
+                    printf("Error: couldn't allocate memory\n");
+                    freeQueue(queueHead);
+                    freeStack(stackHead);
+                    return;
+                }
+            }
+            errorCode = pushToStack(currChar, &stackHead);
+            if (errorCode == -1) {
+                printf("Error: couldn't allocate memory\n");
+                freeQueue(queueHead);
+                freeStack(stackHead);
+                return;
+            }
+        } else if (currChar == '(') {
+            errorCode = pushToStack(currChar, &stackHead);
+            if (errorCode == -1) {
+                printf("Error: couldn't allocate memory\n");
+                freeQueue(queueHead);
+                freeStack(stackHead);
+                return;
+            }
+        } else if (currChar == ')') {
+            while (stackHead != NULL && stackHead->data != '(') {
+                char lastStackOp = popFromStack(&stackHead);
+                if (lastStackOp == '\0') {
+                    printf("Error: trying to put empty operation into queue\n");
+                    freeQueue(queueHead);
+                    freeStack(stackHead);
+                    return;
+                }
+                errorCode = pushToQueue(lastStackOp, &queueHead, &queueTail);
+                if (errorCode == -1) {
+                    printf("Error: couldn't allocate memory\n");
+                    freeQueue(queueHead);
+                    freeStack(stackHead);
+                    return;
+                }
+            }
+            if (popFromStack(&stackHead) != '(') {
+                printf("Error: mismatched parentheses\n");
+                freeQueue(queueHead);
+                freeStack(stackHead);
+                return;
+            }
+        } else if (currChar != ' ') {
+            printf("Error: wrong math expression\n");
+            freeQueue(queueHead);
+            freeStack(stackHead);
+            return;
+        }
+    }
+    while (stackHead != NULL) {
+        char lastStackOp = popFromStack(&stackHead);
+        if (lastStackOp == '\0') {
+            printf("Error: trying to put empty operation into queue\n");
+            freeQueue(queueHead);
+            freeStack(stackHead);
+            return;
+        }
+        errorCode = pushToQueue(lastStackOp, &queueHead, &queueTail);
+        if (errorCode == -1) {
+            printf("Error: couldn't allocate memory\n");
+            freeQueue(queueHead);
+            freeStack(stackHead);
+            return;
+        }
+    }
+
+    printQueue(queueHead);
+    freeQueue(queueHead);
+    freeStack(stackHead);
+    return;
+}
+
+int getPrecedence(char operation) {
+    if (operation == '/' || operation == '*')
+        return 1;
+    else if (operation == '-' || operation == '+')
+        return 0;
+    else
+        return -1;
+}
+
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);
+