#include <stdio.h>

int main(void)

{
	int s,v;
	scanf("%d %d",&s,&v);
	
	int h,m;
	int min,sec;
	
	min=s/v + 10;
	sec=s%v;
	
	if(sec != 0) min++;
	
	if(min<470){
		h=7-min/60;
		m=60-min%60;
		if(m>=10) printf("0%d:%d",h,m);
		else printf("0%d:0%d",h,m);
	}
	
	else {
		
		min-=8*60;
		h=23-min/60;
		m=60-min%60;
		if(m>=10) printf("%d:%d",h,m);
		else printf("%d:0%d",h,m);
	}
	
	
	return 0;

}