diff --git a/du3/program.c b/du3/program.c
new file mode 100644
index 0000000..40802fa
--- /dev/null
+++ b/du3/program.c
@@ -0,0 +1,59 @@
+#include <stdio.h>
+#include <string.h>
+
+#define MAX_LENGTH 100
+
+int check(char* input);
+
+int main() {
+    char input[MAX_LENGTH];
+    while (fgets(input,MAX_LENGTH, stdin)) {
+        if (input[0] == '\n') {
+            break;
+          }
+         input[strcspn(input, "\n")] = '\0';
+         int resultat =check(input);
+         if (resultat ==1) {
+            printf("OK\n");
+          } else {
+             if (resultat == -1) {
+                  printf("ZLE\n");
+              } else {
+                 printf("CHYBA\n");
+             }
+           }
+       }
+    return 0;
+}
+
+int check(char* input) {
+    double number1, number2, resultat, givenResult;
+    char znak;
+    int a=0;
+     a=sscanf(input, " %lf %c %lf = %lf ", &number1, &znak, &number2, &givenResult);
+       if (a != 4) {
+        return 0;
+        }else {
+        switch (znak) {
+            case '+':
+                resultat=number1+number2;
+            break;
+            case '-':
+                resultat=number1-number2;
+            break;
+            case '*':
+                resultat=number1*number2;
+            break;
+            case '/':
+                if (number2 == 0) {
+                    return 0;
+                   }else{resultat=number1/number2;}
+            break;
+            default:
+              }
+       }
+       if (resultat-givenResult ==0 ) {
+        return 1;
+       } else { return -1;
+          }
+ }
\ No newline at end of file