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

int main()
{
	int s,v;
	cin>>s>>v;
	double x=s*1.0/v*1.0;
	int t=10+s/v;
	if(x>s/v||s/v<0)
	{
		t=t+1;	
	}
	int h,y;
	if(t<=480)
	{
		h=(480-t)/60;
		y=(480-t)%60;
		if(h<10&&y>=10)
		{
			cout<<"0"<<h<<":"<<y<<endl;
		}
		else if(h<10&&y<10)
		{
			cout<<"0"<<h<<":"<<"0"<<y<<endl;
		}
		else if(h>=10&&y>=10)
		{
			cout<<h<<":"<<y<<endl;
		}	
	}
	else if(t>480)
	{
		int u=t-480;
		h=u/60;
		if(h==0)
		{
			h=23;
		}
		else
		{
			h=23-h;
		}
		y=60-u%60;
		if(h<10&&y>=10)
		{
			cout<<"0"<<h<<":"<<y<<endl;
		}
		else if(h<10&&y<10)
		{
			cout<<"0"<<h<<":"<<"0"<<y<<endl;
		}
		else if(h>=10&&y>=10)
		{
			cout<<h<<":"<<y<<endl;
		}
	}
	return 0;
}