#include<cstdio>
#include <iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>

#define mod 1000000007;

using namespace std;
typedef long long ll;
typedef pair<ll, ll> Pr;

int N,k;
int w[110];
int dp[101][10001];
int used[110];


int main()
{
	cin >> N;

	ll sum = 0;
	for (int i = 0; i < N; i++) {
		cin >> w[i];
		sum += w[i];
	}

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

	int ans = 0;
	for (int i = 0; i < N; i++) {
		for (int j = 1; j <= 10000; j++) {
			if (j >= w[i] && j <= k) {
				dp[i + 1][j] = dp[i][j];
				if (dp[i + 1][j] < dp[i][j - w[i]] + 1) {
					dp[i + 1][j] = dp[i][j - w[i]] + 1;
					used[i] = 1;
				}
			}
			else if (j < w[i] && j <= k) {
				dp[i + 1][j] = dp[i][j];
			}
		}
	}
	for (int i = 0; i < N; i++) {
		if (used[i])ans += w[i];
	}
	if (ans == k)cout << "possible" << endl;
	else cout << "impossible" << endl;
	return 0;
}