20分，只对了1、2

#include<bits/stdc++.h>
using namespace std;

int main(){
	//freopen("ceshi.in","r",stdin);
	//freopen("ceshi.out","w",stdout);
	int s,v,h,m,hh,mm;
	cin>>s>>v;
	if (s%v==0){
		m=s/v;
	}
	else{
		m=s/v+1;
	}
	m+=10;
	if (m%60==0){
		h=m/60;
	}
	else{
		h=m/60+1;
	}
	hh=8-h;
	if (hh<0){
		hh+=24;
	}
	mm=60-m;
	if (hh==0){
		cout<<"00:";
	}
	if (hh>0 || hh<10){
		cout<<"0"<<hh<<":";
    }
    if (hh>=10){
    	cout<<hh<<":";
	}
	cout<<mm;
}