diff --git a/du4/program.c b/du4/program.c
index ac38d82..63b3799 100644
--- a/du4/program.c
+++ b/du4/program.c
@@ -20,6 +20,7 @@ int main() {
     float b = 0;
     float c = 1;
     int counter = 0;
+    int counter2 = 0;
     float sr= 0;
     int p = 0;
     int check = 0;
@@ -34,6 +35,7 @@ int main() {
                 sym++;
         }
 		if(znaky[i] == '-'){
+			counter2 = 5;
 			if(znaky[i - 1] == ' ' && znaky[i + 1] == ' '){
 			symbol[sym] = znaky[i];
 			znaky[i] = ' ';
@@ -69,13 +71,19 @@ int main() {
 	if(symbol[j] == '=')
 	p = j;
 	}
-	//printf("%d", sym);
+	//printf("--->>%d", sym);
         if(sym == 1){
+		if(counter2 == 5){
 		//printf("a--->>%f\n", a);
 		//printf("b--->>%f\n", b);
 		b = b * -1;
 		sr = a - b;
 	//printf("%f", sr);
+		}
+		else{
+		printf("CHYBA\n");
+		check = 1;
+		}
 	}
      else{
 	if(symbol[p - 1] == '+'){
@@ -106,6 +114,7 @@ int main() {
 	}
 	check = 0;
 	sym = 0;
+    	counter = 0;
     }
     if (feof(stdin)) {
         //printf("Dostal som sa na koniec suboru\n");