560A - Currency System in Geraldion - CodeForces Solution

#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
using namespace std;
/*int solve() {
	int n, ans = -1;
	cin >> n;
	map<int, int>mp;
	for (int i = 1; i <= n; i++) {
		int x;
		cin >> x;
		mp[x]++;
		if (mp[x] >= 3)
			ans = x;
	}
	return ans;
}*/
int main()
{
	/*int t;
	cin >> t;
	while (t--) {
		cout << solve();
		cout << endl;
	}*/
	int n;
	cin >> n;
	vector<int>vec;
	for (int i = 0; i < n; i++) {
		int x;
		cin >> x;
		vec.push_back(x);
		if (vec[i] == 1) {
			cout << -1<<endl;
			exit(0);
		}
	}
	cout << 1<<endl;
}