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

int main() {
	int N, W[100], SUM = 0;
	bool DP[101][5001] = {};
	DP[0][0] = true;
	cin >> N;
	for (int i = 0; i < N; i++) cin >> W[i], SUM += W[i];
	if (SUM % 2 == 1) {
		cout << "impossible" << endl;
		return 0;
	}
	SUM /= 2;
	for (int i = 0; i < N; i++) {
		for (int j = 0; j <= SUM; j++) {
			if (DP[i][j]) DP[i + 1][j] = true;
			if (j >= W[i]) {
				if (DP[i][j - W[i]]) DP[i + 1][j] = true;
			}
		}
	}
	if (DP[N][SUM]) cout << "possible" << endl;
	else cout << "impossible" << endl;
}