#include <stdio.h>
#include <math.h>
int main() 
{int s,v,t,T,time;
scanf("%d %d",&s,&v);
if(s%v!=0)
{t=(s/v)+1;}
else
{t=s/v;}
T=t+10;
time=480-T;
int hour,minute;
hour=time/60;
minute=time%60;
if(hour<10)
printf("0%d:%d",hour,minute);
else
printf("%d:%d",hour,minute);
return 0;
}