#include<stdio.h>
#include<math.h>
int main(void)
{
    int s, v, t1, a, b, n;
    double t0;
    scanf("%d %d", &s, &v);
    t0 = ceil(1.0 * s / v) + 10;
    if (t0 > 24 * 60) return 0;
    else if (t0 < 480)
    {
        t1 = 480 - t0;
        a = t1 / 60;
        b = t1 % 60;
        printf("%02d:%02d", a, b);

    }
    else
    {
        t1 = t0 - 480;
        a = t1 / 60;
        b = t1 % 60;
        printf("%02d:%02d", 23 - a, b);
    }
    return 0;
}