#include<bits/stdc++.h>
using namespace std;

#define ll long long 
#define pb push_back
int main()
{
	string s;
	while(cin>>s)
	{
		string x,y;
		ll n=s.size();
		ll j=n-1;
		for(ll i=0;i<n;i++)
		{
			if(s[i]==s[j]){
				j--;
				x.pb(s[i]);
			}
			else
			{
				j=n-1;
				y+=x;
				y.pb(s[i]);
				x.clear();
				if(s[i]==s[j]){
					y.erase(y.end()-1);
					x.pb(s[i]);
					j--;
				}

			}
		}
		reverse(y.begin(),y.end());
		s+=y;
		
		cout<<s<<endl;
	}

}