#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,a,b,h;
	cin>>n;
	a=n%10*10;
	b=n/10;
	h=a+b;
	if(n>h) cout<<n;
	else cout<<h;
	return 0;
}
/**************************************************************
	Problem: 1625
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/