diff --git a/du3/output/program.exe b/du3/output/program.exe
index b2d48d3..7099261 100644
Binary files a/du3/output/program.exe and b/du3/output/program.exe differ
diff --git a/du3/program.c b/du3/program.c
index dfb1200..dee0e9f 100644
--- a/du3/program.c
+++ b/du3/program.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <ctype.h>
 #define STACK_SIZE 10
 
 
@@ -10,7 +11,13 @@ struct stack {
 };
 
 void push_stack(struct stack* stack, float value) {
-
+    if (stack->size >= STACK_SIZE) {
+        printf("Error!\n");
+        exit(1);
+    }
+    stack->values[stack->size] = value;
+    stack->size++;
+    
 }
 
 float pop_stack(struct stack* stack) {