diff --git a/du4/program.c b/du4/program.c
index 08d7b04..7f10a60 100644
--- a/du4/program.c
+++ b/du4/program.c
@@ -4,6 +4,7 @@
 #include <assert.h>
 #include <math.h>
 #include <ctype.h>
+
 #define LINE_SIZE 150
 
 int main() {
@@ -64,7 +65,16 @@ int main() {
 	if(symbol[j] == '=')
 	p = j;
 	}
-        if(symbol[p - 1] == '+'){
+	printf("%d", sym);
+        if(sym == 1){
+		//printf("a--->>%f\n", a);
+		//printf("b--->>%f\n", b);
+		b = b * -1;
+		sr = a - b;
+	//printf("%f", sr);
+	}
+     else{
+	if(symbol[p - 1] == '+'){
 	sr = a + b; 
 	//printf("%2.f", sr);
 	}
@@ -80,6 +90,7 @@ int main() {
 	sr = a / b; 
 	//printf("%2.f", sr);
 	}
+     }
 	sr = roundf(sr * 100) / 100;
 	if(c == sr){
 	printf("OK\n");
@@ -87,6 +98,7 @@ int main() {
 	else{
 	printf("ZLE\n");
 	}
+	sym = 0;
     }
     if (feof(stdin)) {
         //printf("Dostal som sa na koniec suboru\n");