diff --git a/du4/program.c b/du4/program.c
index 5055940..8992694 100644
--- a/du4/program.c
+++ b/du4/program.c
@@ -6,9 +6,9 @@
 
 int main(){
     char* input = (char*) calloc (100, sizeof(char));
-    char symbol = '\0';
-    int counter = 0;
-    int operation = 0;
+    char symbol;
+    int counter;
+    int operation;
     char* number1 = (char*) calloc (25, sizeof(char));
     char* number2 = (char*) calloc (25, sizeof(char));
     char* result = (char*) calloc (30, sizeof(char));
@@ -55,7 +55,7 @@ int main(){
                         else
                             result += symbol;
                     }
-                    else if(!isdigit(symbol)){
+                    else {
                         printf("CHYBA");
                         goto LABEL;
                     }