#include<stdio.h>
int main(){
	int s,v;
	int t,h;
	scanf("%d %d",&s,&v);
	t=(s-1)/v+11;
	if (t<=60&&t>=50){
	
		printf("07:0%d",60-t);}
	if (t<=50&&t>0){
		printf("07:%d",60-t);}
	if (t>60){
		h=t/60;
		t%=60;
		if (h<=7){
		   if (t<=60&&t>=50){
		   printf("0%d:0%d",7-h,60-t);}
	       if (t<=50&&t>0){
		   printf("0%d:%d",7-h,60-t);}}
		if (h>7&&h<=17) {
		   if (t<=60&&t>=50){
		   printf("%d:0%d",31-h,60-t);}
	       if (t<=50&&t>0){
		   printf("%d:%d",31-h,60-t);}}	
		if (h>=17) {
		   if (t<=60&&t>=50){
		   printf("0%d:0%d",31-h,60-t);}
	       if (t<=50&&t>0){
		   printf("0%d:%d",31-h,60-t);}}	   
		}
	return 0;	
	
	
}