#include<bits/stdc++.h>
using namespace std;
int main()
{
	int s,v,h,a,m;
	cin>>s>>v;
	a=8*60+24*60;
	m=a-ceil(s/v)-10;
	h=m/60;
	m=m%60;
	if(h>23)
		h-=24;
	if(h<10)
		cout<<"0"<<h<<":"<<m-1<<endl;
	else
		cout<<h<<":"<<m-1<<endl;
	return 0;
}