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import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.util.*;

/*
Most frequent bytes

*/

public class Solution {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        String fileName = reader.readLine();

        //create a FileInputStream object bound to fileName
        FileInputStream inputStream = new FileInputStream(fileName);
        Map<Integer, Integer> map = new HashMap<>();
        //Integer count = 0;

        while (inputStream.available() > 0)
        {
            int data = inputStream.read();
            if (map.containsKey(data))
               map.replace(data, map.get(data)+1);
            else {
               map.put(data,1);
            }

        }

        inputStream.close();
        Integer max = 0, max2 = 0;

        for (Map.Entry<Integer,Integer> entry : map.entrySet()) {
            if (entry.getValue() > max) {
                max = entry.getValue();
                if(max > max2) {
                    max2 = max;
                }
            }
        }
        for (Map.Entry<Integer,Integer> entry : map.entrySet()) {
           if(entry.getValue() == max)
               System.out.print(entry.getKey() + "\t ");
        }

    }
}