/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
import java.text.SimpleDateFormat;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		String[] mmss = new String[]{"0:11", "0:54", "0:13", "0:08", "2:31"};
		
		SimpleDateFormat sdf = new SimpleDateFormat("mm:ss");
		long total = 0;
		for(int i = 0; i < mmss.length; i++)
		{
			total += sdf.parse(mmss[i]).getTime();
		}
		System.out.println(sdf.format(new Date(total/mmss.length)));
	}
}