#include<bits/stdc++.h>
using namespace std;
 
int main(){
    int n,a,b;
    cin>>n;
    a=n%10;
    b=n/10%10;
    if(a>b){
        cout<<a;
    }else{
        cout<<b;
    }
     
    }
/**************************************************************
	Problem: 1622
	User: chenjiahui
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/