#include <iostream>

#include <vector>

using namespace std;

int main()

{

	// fast io

	ios::sync_with_stdio(false);

	cin.tie(nullptr);

	cout.tie(nullptr);

	int N, a;	

	while (cin >> N)

	{

		// store data

		vector<int> data;

		for (int i = 0; i < N; ++i) cin >> a, data.emplace_back(a);

		// i start with the smallest number

		for (int i = min(data[0], data[N - 1]); i > 0; --i)

		{

			// copy the original data

			vector<int> cpy = data;

			int left = 0, right = N - 1;

			int tmp = i;

			while (right >= 0 && left < N && cpy[left] >= tmp && cpy[right] >= tmp)

			{

				if ((cpy[left] -= tmp) == 0) ++left;

				if ((cpy[right] -= tmp--) == 0) --right;

				if (tmp == 0)

				{

					int sum = 0;

					for (auto& j : cpy) sum += j;

					// if i = 1, thete are only two cases: 1 2 and 2 1 1

					if (!(sum & 1) && i != 1 || sum == 0 && i == 1) cout << i << "\n";

					else cout << "no quotation\n";

					goto finish;				

				}

			}

		}

		finish:;

	}

	return 0;

}