#include<stdio.h>
#include<math.h>
int main(){
 int s,v;
 scanf("%d %d",&s,&v);
 int t=s/v;
 if(s%v==0) t=s/v+10;
 else t=s/v+11;
 if(t<=50)printf("07:%d",60-t);
 if(50<t&&t<=60)printf("07:0%d",60-t);
 if(t>60&&t<8*60){
    if(t%60==0)printf("0%d:00",7-(t/60));
 	if(t%60<=50)printf("0%d:%d",7-(t/60),60-(t%60));
 	if(50<t%60&&t%60<=60) printf("0%d:0%d",7-(t/60),60-(t%60));
 }
if(t==8*60) printf("00:00");
if(t>8*60&&t<20*60){
    if(t%60==0)printf("%d:00",24+8-(t/60));
 	if(t%60<=50)printf("%d:%d",24+7-(t/60),60-(t%60));
 	if(50<t%60&&t%60<=60) printf("%d:0%d",24+7-(t/60),60-(t%60));
 }
if(t==20*60)printf("12:00");
if(t>20*60){
    if(t%60==0)printf("0%d:00",24+8-(t/60));
 	if(t%60<=50)printf("0%d:%d",24+7-(t/60),60-(t%60));
 	if(50<t%60&&t%60<=60) printf("0%d:0%d",24+7-(t/60),60-(t%60));
 }

	return 0;
}