// P5707
# include <cstdio>
using namespace std;

int main()
{
    int s, v, t;
    scanf("%d %d", &s, &v);
    if(s % v == 0)
        t = (s / v);
    else
        t = (s / v) + 1;
    if(t >= 24 * 60) t -= 24 * 60;
    int t2 = 480;
    t = t2 - 10 - t;
    int x, f;
    x = t / 60;
    f = t % 60;
    printf("%02d%c%02d", x, ':', f);
    return 0;
}