#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,m,t;
    cin>>n;
    m=n/10;
    t=n%10;
    if(m>t) cout<<m;
    else cout<<t;
}//1674
/**************************************************************
	Problem: 1622
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/