#include <iostream>
using namespace std;
int n,x,g=0,i;

int main()
{

    cin >> n;
    while(g==0 && cin>> x)
            if(x%2==0)
            {
                g=1;
                cout << x;
            }
    if(g==0)
        cout << "IMPOSIBIL";
    return 0;
}