diff --git a/du3/program.c b/du3/program.c
index 8ebc785..305fa21 100644
--- a/du3/program.c
+++ b/du3/program.c
@@ -2,7 +2,7 @@
 #include<stdlib.h>
 #include <string.h>
 #include <assert.h>
-#define STACK_SIZE 10000
+#define STACK_SIZE 10
 
 struct stack{
     float values[STACK_SIZE];
@@ -65,6 +65,10 @@ void process_operations(struct stack* stack) {
                 return;
             }
         } else {
+            if(stack->size == STACK_SIZE){
+                printf("full stack\n");
+                return;
+            }
             char *endptr;
             if (line[0] == '.')
             { printf("bad input\n");