#include<stdio.h>
#include<math.h>
int main()
{
	int time,s,c,v,m,H,M;
	double t;
	scanf("%d%d", &s, &v);
	t = 1.0 * s / v;
        t = round(t + 0.5);
	time = t;
	if (time <= 470)
	{
		m = 470 - time;
	}
	else
	{
		m = 1910 - time;//考虑一天前的情况
	}
	M = m % 60;
	H = (m - M) / 60;
	if(H<10)
	{
		if(M<10)
		{
			printf("0%d:0%d", H, M);
		}
		else
		{
			printf("0%d:%d", H, M);
		}
	}
	else     
	{
		if (M < 10)
		{
			printf("%d:0%d", H, M);
		}
		else
		{
			printf("%d:%d", H, M);//分类讨论0H:0M,0H:MM,HH:0M,HH:MM的情况
		}
	}
}