#include <bits/stdc++.h>

int main(){
    using namespace std;
    unsigned long N;
    cin >> N;
    if(N & 1){
        if(N == 1){
            unsigned long A;
            cin >> A;
            cout << A << endl;
        }else puts("1");
        return 0;
    }
    set<unsigned long> pq(istream_iterator<unsigned long>{cin}, istream_iterator<unsigned long>{});
    unsigned long a{*begin(pq)};
    pq.erase(begin(pq));
    unsigned long b{*begin(pq)};
    pq.erase(begin(pq));
    cout << a * b << endl;
    return 0;
}