大佬看看我哪里不对了

#include <cstdio>
int main(){
    long long s, v;
    scanf("%lld %lld", &s, &v);
    int k = s/v*v==s?s/v:s/v+1;
    printf("0%d:", (470-k)/60);
    if((470-k)%60<=9) printf("0%d", (470-k)%60);
    else printf("%lld", (470-k)%60);
    return 0;
}