#include <iostream> #include <algorithm> #define ull unsigned long long using namespace std; ull a[500100], b[500100]; int main() { ull n; cin >> n; while(n) { for(ull i = 1; i <= n; i++) cin >> a[i]; sort(a + 1, a + n + 1); for(ull i = 1; i <= n; i++) b[i] = a[i]; int maxn = 0, minn = 0; for(ull i = 2; i <= n; i++) { ull t = a[i] * a[i - 1] + 1; a[i - 1] = 0; a[i] = t; } for(ull i = n - 1; i >= 1; i--) { ull t = b[i + 1] * b[i] + 1; b[i + 1] = 0; b[i] = t; } maxn = a[n]; minn = b[1]; cout << maxn - minn << endl; cin >> n; } return 0; }