#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main()
{
    int s = 0;
    int v = 0;
    scanf("%d%d", &s, &v);
    
    int t = 0;
    if (s / v == 0)
    {
        t = s / v;
        t += 9;
    }
    else
    {
        t = s / v;
        t += 10;
    }
    
    int H = 7;
    int M = 59;
    
    while (t > 0)
    {
        if (H > 0)
        {
            if (M > 0)
            {
                M--;
            }
            else
            {
                M = 59;
                H--;
            }
        }
        else
        {
            H = 23;
            M = 59;
        }
        t--;
    }
    
    int h1 = 0;
    int h2 = 0;
    int m1 = 0;
    int m2 = 0;
    
    h1 = H / 10;
    h2 = H - (h1 * 10);
    m1 = M / 10;
    m2 = M - (m1 * 10);
    
    printf("%d%d:%d%d", h1, h2, m1, m2);
    
    return 0;
}