/**

 *

 *作者:Ycute

 *时间:2019-11-02-11.19.47

 *题目题意简单描述:无

 */

 #include<iostream>

 #include<cmath>

 #include<cstring>

 #include<algorithm>

 #include<vector>

 using namespace std;

 int main(){

     int c1,c2;

     scanf("%d %d",&c1,&c2);

     double temp=(c2-c1)*1.0/;

     int s=(int)(temp+0.5);

     int hh=s/;

     int mm=s%/;

     int ss=s%;

     printf("%02d:%02d:%02d\n",hh,mm,ss);

     return ;

 }