import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
  public static void main(String[] args) throws IOException{
	  BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(System.in));
	  String[] datas=bufferedReader.readLine().split(" ");
//	  *1.0确保前面的数是double类型，加上0.5作为四舍五入的处理
	  int seconds=(int)((Integer.parseInt(datas[1])-Integer.parseInt(datas[0]))*1.0/100+0.5);
	  int hour=seconds/3600;
	  int minute=seconds%3600/60;
	  int second=seconds%60;
	  System.out.printf("%02d:%02d:%02d",hour,minute,second);
	  bufferedReader.close();
  }
}