#include<iostream>
using namespace std;
int main()
{
	int s=0, v=0,b=0,d=0,shi,shi1,fen,fen1;
	cin>>s>>v;
	double a = 470 - 1.0 * s / v;
	double c = 970 + 1.0 * s / v;
	//后面直接从七点五十开始算时间
	if (1.0 * s / v <= 470)//470-1.0*s/v is left time			
	{
		b = (int)a;
		shi = b / 60 / 10; shi1 = b / 60 % 10;
		fen = b % 60 / 10, fen1 = b % 60 % 10;
		cout << shi << shi1 << ":" << fen << fen1;
	}
		if (1.0 * s / v > 470) {
			d = (int)c;
			shi = d / 60 / 10; shi1 = d / 60 % 10;
			fen = d % 60 / 10, fen1 = d % 60 % 10;
			cout << shi << shi1 << ":" << fen << fen1;
		}
	return 0;
}