diff --git a/cv3/program.c b/cv3/program.c
index 2901184..6b4ca47 100644
--- a/cv3/program.c
+++ b/cv3/program.c
@@ -23,7 +23,7 @@ int main(){
         fgets(line, 100, stdin);
         chcf = strtok(line,"\n");
         cf = strtod(line,NULL);
-        if(chcf != 0x0){
+        if(chcf != NULL){
             chcf1 = *chcf;
         }
         if(chcf1 >='A' && line[0] != '\n'){