import java.util.*; |
public class Main { |
public static void main(String[] args) |
{ |
Scanner scan = new Scanner(System.in); |
String N = scan.next(); |
char max = '0' ; |
for ( int i = 0 ; i < N.length(); i++) |
{ |
if (N.charAt(i) > max) |
max = N.charAt(i); |
} |
System.out.println(max); |
} |
} |