#include <iostream>
using namespace std;
int main()
{
int n; cin >> n;
int *a = new int[n];
long long ans = 1;
for(int i = 0; i < n; i++){
cin >> a[i];
if(a[i] % 8 == 0 && a[i] % 24 != 0) ans *= a[i];
}
if(ans == 1) cout << "-1";
else cout << ans;
return 0;
}
