diff --git a/du4/program.c b/du4/program.c
new file mode 100644
index 0000000..d5860cd
--- /dev/null
+++ b/du4/program.c
@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+int call(double A, double B, double C, char AC){
+    if(AC=='/'&&B==0){
+        return printf("CHYBA");;
+    }
+    if(AC=='+'){
+        if(A+B==C)return printf("OK");
+        return printf("ZLE");
+    }
+    if(AC=='-'){
+        if(A-B==C)return printf("OK");
+        return printf("ZLE");
+    }
+    if(AC=='*'){
+        if(A*B==C)return printf("OK");
+        return printf("ZLE");
+    }
+    if(AC=='/'){
+        if(A/B==C)return printf("OK");
+        return printf("ZLE");
+    }    
+}
+
+int main()
+{
+    
+
+char *str;
+str=(char*)malloc(100);
+double a=1,b,c;
+char ac;
+scanf("%s",str);
+sscanf(str,"%lf%c%lf=%lf",&a,&ac,&b,&c);
+//printf("%d%c%d=%d",a,ac,b,c);
+call(a,b,c,ac);
+//if(result)
+    return 0;
+}