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();
}
}