#include<stdio.h>
int main()
{
    int s,v;
    scanf("%d %d",&s,&v);
    int time,pretime;
    if(s%v==0)
    time=s/v;
    else{
    time=(s/v)+1;
    }
    pretime=time+10;
    int needhour,needmin;
    needhour=pretime/60;
    needmin=pretime%60;
    if(needmin==0){
        if(needhour>0&&needhour<8)
        printf("0%d:00",8-needhour);
        if(needhour==8)
        printf("00:00");
        if(needhour>8)
        printf("%d:00",24+8-needhour);
    }
    if(needmin!=0){
        if(needhour>0&&needhour<8)
        printf("0%d:%d",7-needhour,60-needmin);
        if(needhour==8)
        printf("23:%d",60-needmin);
        if(needhour>8)
        printf("%d:%d",24+7-needhour,60-needmin);
        if(needhour==0)
        printf("7:%d",60-needmin);
    }
}