#include <math.h>
#include <stdio.h>
int main() {
    int s, v;
    scanf("%d %d", &s, &v);
    int start = (int)((24 + 8) * 60 - 10 - ceil(1.0 * s / v)) % (24 * 60);
    double m = start / 60, n = start % 60;
    printf("%02.0lf:%02.0lf", m, n);
    return 0;
}

#include <stdio.h>

void calculateTime(int s, int v) {
    double t1 = (double)s / v;
    int c = t1;
    double b = t1 - c;

    int totalMinutes = (int)(t1 + 10);
    int hours = totalMinutes / 60;
    int minutes = totalMinutes % 60;
    if (hours <= 7)
        printf("%02d:", 7 - hours);
    else
        printf("%02d:", 24 - (hours - 7));
    if (b != 0) {
        printf("%02d", 59 - minutes);
    } else
        printf("%02d", 60 - minutes);
}

int main() {
    int s, v;
    scanf("%d %d", &s, &v);
    calculateTime(s, v);
    return 0;
}