#include <iostream>
int main() {
    int s, v;
    scanf("%d%d", &s, &v);

    int need = (s + v - 1) / v + 10; 
    int total = 8 * 60 - need;       
    int h = total / 60;
    int m = total % 60;

    if (m < 0) h--, m += 60;         
    if (h < 0) h += 24;

    printf("%02d:%02d\n", h, m);
    return 0;
}