diff --git a/cv3/program.c b/cv3/program.c
new file mode 100644
index 0000000..1c85e15
--- /dev/null
+++ b/cv3/program.c
@@ -0,0 +1,105 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <ctype.h>
+
+#define STACK_SIZE 10
+
+struct stack {
+    float values[STACK_SIZE];
+    int size;
+};
+
+
+void push_stack(struct stack* stack, float value);
+float pop_stack(struct stack* stack);
+void print_stack(struct stack* stack);
+int is_number(const char* str);
+
+
+int main() {
+    struct stack mystack;
+    memset(&mystack, 0, sizeof(struct stack)); 
+
+    char input[50];
+    while (1) {
+        printf("Enter a number or an operator (+, -, *, /): ");
+        if (!fgets(input, sizeof(input), stdin)) {
+            break; 
+        }
+        
+        input[strcspn(input, "\n")] = 0;
+
+        if (is_number(input)) {
+            
+            float value = atof(input);
+            push_stack(&mystack, value);
+        } else if (strlen(input) == 1 && strchr("+-*/", input[0])) {
+            
+            float b = pop_stack(&mystack);
+            float a = pop_stack(&mystack);
+            float result;
+
+            switch (input[0]) {
+                case '+':
+                    result = a + b;
+                    break;
+                case '-':
+                    result = a - b;
+                    break;
+                case '*':
+                    result = a * b;
+                    break;
+                case '/':
+                    if (b == 0) {
+                        fprintf(stderr, "Error: Division by zero.\n");
+                        exit(EXIT_FAILURE);
+                    }
+                    result = a / b;
+                    break;
+                default:
+                    fprintf(stderr, "Error: Invalid operator.\n");
+                    exit(EXIT_FAILURE);
+            }
+            push_stack(&mystack, result);
+        } else {
+            fprintf(stderr, "Error: Invalid input.\n");
+            exit(EXIT_FAILURE);
+        }
+
+        
+        print_stack(&mystack);
+    }
+
+    return 0;
+}
+
+
+void push_stack(struct stack* stack, float value) {
+    assert(stack->size < STACK_SIZE); 
+    stack->values[stack->size] = value;
+    stack->size += 1;
+}
+
+
+float pop_stack(struct stack* stack) {
+    assert(stack->size > 0); 
+    stack->size -= 1;
+    return stack->values[stack->size];
+}
+
+
+void print_stack(struct stack* stack) {
+    for (int i = 0; i < stack->size; i++) {
+        printf("%.2f ", stack->values[i]);
+    }
+    printf("\n");
+}
+
+
+int is_number(const char* str) {
+    char* endptr;
+    strtod(str, &endptr);
+    return *endptr == '\0' && endptr != str;
+}