#include<bits/stdc++.h>
using namespace std;
int main() { 
  int n,a,b;
  cin>>n;
  a=n/1%10;
  b=n/10%10; 
  if (a>b) cout<<a;
  else cout<<b;
    return 0;
}
/**************************************************************
	Problem: 1040
	User: wangyousi
	Language: C++
	Result: Wrong Answer
****************************************************************/