#include<iostream>
using namespace std;

int n, a[101], dp[101][5001];

int solve(int i, int m)
{
	if (dp[i][m] > -1) return dp[i][m];

	if (m == 0) dp[i][m] = 1;
	else if (i >= n)  dp[i][m] = 0;
	else if (solve(i + 1, m)) dp[i][m] = 1;
	else if (solve(i + 1, m - a[i])) dp[i][m] = 1;
	else dp[i][m] = 0;

	return dp[i][m];
}

int main()
{
	int i, j, sum = 0;
	cin >> n;

	for (i = 1; i <= n; i++)
	{
		cin >> a[i];
		sum += a[i];
	}

	if (sum % 2 == 1)
	{
		cout << "impossible" << endl;
		return 0;
	}

	for (i = 0; i <= n; i++)
	{
		for (j = 0; j <= sum / 2; j++)
		{
			dp[i][j] = -1;
		}
	}

	if (solve(0, sum / 2)) cout << "possible" << endl;
	else cout << "impossible" << endl;
}