#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: 1625
	User: zhengzihao3
	Language: C++
	Result: Wrong Answer
****************************************************************/