#include <bits/stdc++.h>
using namespace std;
int s,v,stime=8*60+24*60,h,n;
int main (){
	cin >> s >> v;
	if(s%v!=0) stime--;
	stime=stime-s/v-10;
	if(stime>=24*60)stime=stime-24*60;
	h=stime/60;
	n=stime%60;
	cout << h << ":";
	if(n==0) cout<< "00";
	else if(n<10) cout << "0" << n;
	else cout<< n;
	return 0;
}