package com.javarush.task.task18.task1804;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;/*
Самые редкие байты
*/
import java.util.HashMap;
import java.util.Map;

public class Solution {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String nameFile = reader.readLine();
        Map<Integer,Integer> map = new HashMap<>();
        FileInputStream fileInputStream = new FileInputStream(nameFile);

        int min = Integer.MAX_VALUE;
        while (fileInputStream.available() >0){
            int data = fileInputStream.read();
            int value = map.getOrDefault(data,0)+1;
            map.put(data,value);
            if(value < min){
                min = value;
                }
        }
         //System.out.println(map);
        for (Map.Entry<Integer,Integer> entry : map.entrySet()){
            if(min == entry.getValue()){
                System.out.print(entry.getKey() + " ");
            }
        }
        fileInputStream.close();
    }
}