Help me in solving CLB055 problem

help
,
1

My issue

why is it error

My code

#include <stdio.h>

int main() {
    int a, b;
    int sum;
    int diff;
    a=35;
    b=23;
sum=a+b;
diff=a-b;
printf("Sum is:%d\n",sum);
printf("Difference is:%d",diff);
return 0;
}

Learning course: Programming and Problem solving using C
Problem Link: https://www.codechef.com/learn/course/ciet-programming-c/CIETPC13/problems/CLB055