#include<bits/stdc++.h> 
using namespace std;
int main()
{
	int n,g,s;
	cin>>n;
	g=n%10;
	s=n/10;
	n=g+s;
	if(g>s){
		cout<<g;
	}else{
		cout<<s;
	}
	 
    
}
/**************************************************************
	Problem: 1622
	User: yangjunwen
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/