#include "stdio.h"
#include "math.h"
int main() {
    int s,v,t;
    int h,m,m1=7*60+50;
    scanf("%d%d",&s,&v);
    t=s/v;
    if(s%v)
        t+=1;
    m1-=t;
    if(fabs(m1)>24*60) {
        m1=fabs(m1);
        m1 %= 24 * 60;
    }
    m=m1%60;
    h=m1/60;
    printf("%02d:%02d",h,m);
    return 0;
}