那位大佬再来帮我一下啊，全WA了，帮助必关！

#include<bits/stdc++.h>
#include<stdio.h>
using namespace std;
int main(){
	int s,v,t,di,fe;
	cin>>s>>v;
	t=s/v+10;
	if(t<480){
		t=480-t;
		di=t/60;
		fe=t%60;
		cout<<di;
		cout<<":";
		cout<<fe;
	}
	if(t>480){
		t=24*60+480-t;
		di=480/60;
		fe=480%60;
		cout<<di;
		cout<<":";
		cout<<fe;
	}
	if(t==480){
		cout<<"00:00";
	}
    return 0;
}