#include<bits/stdc++.h>
using namespace std;
int main(){
    int l,g,s;
    cin>>l;
    g=l%10;
    s=l/10;
    if(s>g){
        cout<<s;
    }else{
        cout<<g;
    }
     
}
/**************************************************************
	Problem: 1622
	User: zhangyilei
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/