#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,g,s;
	cin>>n;
	g=n%10*10;
	s=n/10%10;
	if((g+s)>n) cout<<g+s;
	if(n>(g+s)) cout<<n;
	return 0;
}

/**************************************************************
	Problem: 1625
	User: panjinyan
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/