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