#include <iostream>
using namespace std;
int n,nr,nr1,x,t,Nr=0;
int oglindit(int x)
{
int ogl=0;
while(x!=0)
{
ogl=ogl*10+x%10;
x=x/10;
}
return ogl;
}
int main()
{
cin>>n;
nr=0;
x=n;
while(x!=0)
{
nr++;
x=x/10;
}
nr1=0;
while(n!=0)
{
t=n%10;
nr1++;
if(nr1!=(nr/2)+1)
{
Nr=Nr*10+t;
}
n=n/10;
}
cout<<oglindit(Nr);
}