#include<stdio.h>
int main()
{
     int  c,a,q,s,v,t=8*60;
     scanf("%d%d",&s,&v);
     q=s/v+11;
     a=t-q;
    while(a<0)
    {
       t=24*60;
       a=t+a;
   }
      q=a;
      q=q/60;
      c=a%60;
      a=q;
   
   if(a<10&&c<10)
     printf("0%d:0%d",a,c);
   if(a<10&&c>=10)
     printf("0%d:%d",a,c);
   if(a>=10&&c<10)
     printf("%d:0%d",a,c);
   if(a>=10&&c>=10)
      printf("%d:%d",a,c);
    return 0;
}