我到底哪个地方不对啊，90分

#include<iostream>
int s,v,total,timer;
int  main()
{
    std::cin>>s>>v;
    if(s/v!=0){
        timer=s/v+11;
    }else timer=s/v+10;
    if(timer>8*60) total=24*60-(timer-8*60);
    else total=8*60-timer;
    int a=total/60,b=total%60;
    if(a<10){
        if(b<10) std::cout<<'0'<<a<<":0"<<b;
        else std::cout<<'0'<<a<<':'<<b;
    }
    else {
        if(b<10) std::cout<<a<<":0"<<b;
        else std::cout<<a<<':'<<b;
    }
    return 0;
}