package com.sort;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Test1 {

    public static void main(String[] args) { 
        @SuppressWarnings("resource")
        Scanner scan = new Scanner(System.in);
        String str = scan.nextLine();
        ArrayList arr = new ArrayList<>();
        for(int i = 0 ; i < str.length() ; i ++){
            if(!Character.isDigit(str.charAt(i))){
                String s = str.replace(str.charAt(i), ' ');
                str = s;
            }
        }
        String[] ss = str.split(" ");
        for(String sd : ss){
            if(sd!=null){
                arr.add(sd);
            }
        }
        Collections.sort(arr);
        System.out.println(arr.get(arr.size()-1));
    }
}
第一题