diff --git a/cv3/program.c b/cv3/program.c
index 799a97b..7fdb5d3 100644
--- a/cv3/program.c
+++ b/cv3/program.c
@@ -81,11 +81,15 @@ int main(int argc, char const *argv[])
         {
             break;
         }
-        if(isalpha(buf) != 0)
+        for (int i = 0; i < strcspn(buf, "\n"); i++)
         {
-            printf("bad input\n");
-            return 0;
+            if(isalpha(buf[i]) != 0)
+            {
+                printf("bad input\n");
+                return 0;
+            }
         }
+        
         buf[strcspn(buf, "\n")] = '\0';
         if(!check_op(buf[0]))
         {