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