#include<bits/stdc++.h>
using namespace std;
inline int read()
{
	int x=0,f=1;char ch=getchar();
	while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();}
	while (ch>='0'&&ch<='9'){x=x*10+ch-48;ch=getchar();}
	return x*f;
}
int s,v,h=7;
int mn=50,kc;
int main(){
	s=read();
	v=read();
	if(s%v){
		kc=s/v+1;
	}else{
		kc=s/v;
	}
	mn-=kc;
	while(mn<0){
		mn+=60;
		h-=1;
		if(h==0){
			h=24;
		}
	}
	if(h<10){
		if(mn>=10){
			cout<<0<<h<<":"<<mn;
		}else{
			cout<<0<<h<<":"<<0<<mn;
		}
	}else{
		if(mn>=10){
			cout<<h<<":"<<mn;
		}else{
			cout<<h<<":"<<0<<mn;
		}
	}
    return 0;
}