#include<bits/stdc++.h>
using namespace std;

int n,w[100],sum;

bool dfs(int i, int weight) {
	if (i == n) return weight == sum / 2;
	if (dfs(i + 1, weight)) return true;
	if (dfs(i + 1, weight + w[i])) return true;
	return false;
}

void solve() {
	if (sum % 2 != 0) {
		cout << "impossible" << endl;
	}else {
		if (dfs(0, 0)) cout << "possible" << endl;
		else cout << "impossible" << endl;
	}
}

int main() {
	cin >> n;
	sum = 0;
	for (int i = 0; i < n; i++) {
		cin >> w[i];
		sum += w[i];
	}
	solve();
}