diff --git a/cv3/program.c b/cv3/program.c
index 7fdb5d3..37fcc86 100644
--- a/cv3/program.c
+++ b/cv3/program.c
@@ -81,6 +81,11 @@ int main(int argc, char const *argv[])
         {
             break;
         }
+        if(buf[0] == '.')
+        {
+            printf("bad input\n");
+            return 0;
+        }
         for (int i = 0; i < strcspn(buf, "\n"); i++)
         {
             if(isalpha(buf[i]) != 0)