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#include <bits/stdc++.h>
#define int long long
using namespace std;
int ans=470; 
signed main() {
	ios::sync_with_stdio(0);
	cout.tie(0);
	cin.tie(0);
	int v,s;
	cin>>v>>s;
	ans-=(v/s)+(v%s)*1;
	if(ans<0)
	{
		ans+=(24*60);
	}
//	cout<<ans;
	int h=ans/60,m=ans%60;
	if(h<10)
	{
		cout<<0;
	}
	cout<<h<<":";
	if(m<10)
	{
		cout<<0;
	}
	cout<<m;
	return 0;
}