#include <bits/stdc++.h>

using namespace std;

int main() {
	int n;
	cin >> n;
	int sum = 0;
	int w[100];
	bool dp[10000];
	for (int i = 0;i < 10000;i++) {
		dp[i] = false;
	}
	for (int i = 0;i < n;i++) {
		cin >> w[i];
		sum += w[i];
	}
	if (sum % 2 == 1) {
		cout << "impossible" << endl;
		return 0;
	}

	int half = sum / 2;
	dp[0] = true;
	for (int i = 0;i < n;i++) {
		for (int j = half;j >= w[i];j--) {
			dp[j] = dp[j] | dp[j - w[i]];
		}
	}
	if (dp[half]) {
		cout << "possible" << endl;
	}
	else {
		cout << "impossible" << endl;
	}


	return 0;
}