#include<stdio.h>
#include<math.h>
int main()
{
    int s,v,time,hour,minute;
    scanf("%d %d",&s,&v);
    if(s%v==0)
    {
        time=s/v;
    }
    else
    {
        time=((int)(s/v))+1;    
    }
    if(470-time>0)
    {
        hour=7-(time/60);
        minute=50-(time%60);
        if(minute<10)
        printf("0%d:0%d",hour,minute);
        else
        printf("0%d:%d",hour,minute);
    }
    else
    {
        time=abs(470-time);  
        hour=23-(time/60);
        minute=60-(time%60);
        if(minute==0)
        {        
            hour++;
            if(hour<10)
            printf("0%d:00",hour);
            else
            printf("%d:00",hour);
        }
        else if(minute<10&&minute!=0)
        {
            if(hour<10)
            printf("0%d:0%d",hour,minute);
            else
            printf("%d:0%d",hour,minute);
        }
        else
        {
            if(hour<10)
            printf("0%d:%d",hour,minute);
            else
            printf("%d:%d",hour,minute);
        }
    }
    return 0;
}