#include<bits/stdc++.h>
using namespace std;
int n,g,s,c;
int main(){
	cin>>n;
	g=n/1%10;
	s=n/10%10;
	c=g*10+s;
	if(n>c){
		cout<<n;
	}
	if(n<c){
	    cout<<c;
	}
	
	return 0;
}

/**************************************************************
	Problem: 1625
	User: wuhanyu
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/