最大数字

package asda;
import java.util.Scanner;
public class Main
{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        String s = scan.nextLine();
        int l = s.length();
        int max = 0;
        for(int i=0; i < l; ++i)
            if(s.charAt(i)>max)
                max = s.charAt(i);  	
        max-=48;
        System.out.println(max);
    }
}