#3#5不过

#include<iostream>
#include<math.h>
using namespace std;
int main(){
    int a,b,c,hour=0,min=0;
    cin>>a>>b;
    c=ceil(((double)a)/b)+10;
    min=c%60;
    hour=c/60+1;
    if(min==0)
    {
        min+=60;
        hour-=1;
    }
    if(c<480)
    {
        cout<<"0"<<8-hour<<":";
        if(min==60) cout<<"00";
        else cout<<60-min;
    }
    else
    {
            hour-=8;
            if(24-hour<10) cout<<"0";
            cout<<24-hour<<":";
            if(min==60) cout<<"00";
            else cout<<60-min;
    }
    return 0; 
}

不知道为什么#3#5输出比标准多1 求调