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

/**************************************************************
	Problem: 1734
	User: admin
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2072 kb
****************************************************************/