#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;
    }
    vector<unsigned long> A(N);
    copy_n(istream_iterator<unsigned long>{cin}, N, begin(A));
    nth_element(begin(A), begin(A) + 1, end(A));
    cout << A[0] * A[1] << endl;
    return 0;
}