diff --git a/program.c b/program.c
index e1347fc..de0abc5 100644
--- a/program.c
+++ b/program.c
@@ -1,9 +1,18 @@
 #include <stdio.h>
-#include "stdlib.h"
+#include <stdlib.h>
+#include <ctype.h>
+
 int main() {
     char* prve_cislo = malloc(100* sizeof(char));
     char* druhe_cislo = malloc(100* sizeof(char));
     fgets(prve_cislo,100,stdin);
+    if (isalpha(*prve_cislo)){
+        printf("%s je neplatny zapis.\n",prve_cislo);
+        free(prve_cislo);
+        free(druhe_cislo);
+        return 0;
+
+    }
     int cislo1 = strtof(prve_cislo,NULL);
     int cislo2;
     while((fgets(druhe_cislo,100,stdin))){
@@ -20,4 +29,5 @@ int main() {
     }
 
    free(prve_cislo);
+    free(druhe_cislo);
 }
\ No newline at end of file