#include <bits/stdc++.h>
using namespace std;
int main(){
	int a,s,d,k;
	cin>>a;
	s=a%10;
	d=a/10%10;
	k=s*10+d;
	if(k>a){
		cout<<k;
	}else{
		cout<<a;
	}
}

/**************************************************************
	Problem: 1734
	User: tonghuawei
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/