//注意24小时这个问题
#include<bits/stdc++.h>
using namespace std;
int main()
{
    int s,v,sum,hour,min,timehour,timemin;
    cin>>s>>v;
    sum=s/v;
    hour=sum/60;
    min=sum%60+11;
    if(min>=60){
        hour=hour+1;
        if(hour<8){//今天出发
            timemin=60-min;
            if(timemin==0){
                timehour=8-hour;
                cout<<"0"<<timehour<<":"<<"0"<<timemin;
            }
            else if(timemin<10){
                timehour=7-hour;
                cout<<"0"<<timehour<<":"<<"0"<<timemin;
            }
            else{
                timehour=7-hour;
                cout<<"0"<<timehour<<":"<<timemin;
            };
        }
        else if(8<=hour&&hour<=22){//昨天10点出发
        
            timemin=60-min;
            if(timemin==0){
                timehour=32-hour;
                cout<<timehour<<":"<<"0"<<timemin;
            }
            else if(timemin<10){
                timehour=31-hour;
                cout<<timehour<<":"<<"0"<<timemin;
            }
            else{
                timehour=31-hour;
                cout<<timehour<<":"<<timemin;
            };
        }   
        else if(22<hour&&hour<24){
            
            timemin=60-min;
            if(timemin==0){
                timehour=32-hour;
                cout<<"0"<<timehour<<":"<<"0"<<timemin;
            }
            else if(timemin<10){
                timehour=31-hour;
                cout<<"0"<<timehour<<":"<<"0"<<timemin;
            }
            else{
                timehour=32-hour;
                cout<<"0"<<timehour<<":"<<timemin;
            };       
        }
    }
    else{
        if(hour<8){//今天出发
            timemin=60-min;
            if(timemin==0){
                timehour=8-hour;
                cout<<"0"<<timehour<<":"<<"0"<<timemin;
            }
            else if(timemin<10){
                timehour=7-hour;
                cout<<"0"<<timehour<<":"<<"0"<<timemin;
            }
            else{
                timehour=7-hour;
                cout<<"0"<<timehour<<":"<<timemin;
            };
        }
        else if(8<=hour&&hour<=22){//昨天10点出发
            
            timemin=60-min;
            if(timemin==0){
                timehour=32-hour;
                cout<<timehour<<":"<<"0"<<timemin;
            }
            else if(timemin<10){
                timehour=31-hour;
                cout<<timehour<<":"<<"0"<<timemin;
            }
            else{
                timehour=31-hour;
                cout<<timehour<<":"<<timemin;
            };
        }   
        else if(22<hour&&hour<24){
            
            timemin=60-min;
            if(timemin==0){
                timehour=32-hour;
                cout<<"0"<<timehour<<":"<<"0"<<timemin;
            }
            else if(timemin<10){
                timehour=31-hour;
                cout<<"0"<<timehour<<":"<<"0"<<timemin;
            }
            else{
                timehour=32-hour;
                cout<<"0"<<timehour<<":"<<timemin;
            };       
        }
    }
    //差一步min大于一个小时进一
    return 0;    
        
}