#include<vector>
#include<iostream>
#include<algorithm>
using namespace std;
static const int MAX_N = 100;
int main() {
	int N;
	cin >> N;
	vector<int>w(N);
	for (int i = 0; i < N; i++) {
		cin >> w[i];
	}
	int all = 0;
	for (int i = 0; i < N; i++) {
		all += w[i];
	}
	int sum = all / 2;
	if (all % 2 != 0) {
		cout << "impossible" << endl;
		return 0;
	}
	vector<vector<int>>dp(N, vector<int>(sum+1, false));//i番目まで重りを見て、合計jグラムになるかどうか
	for (int i = 0; i < N ; i++) {
		dp[i][0] = true;
	}
	for (int i = 0; i <= N - 2; i++) {
		for (int j =0 ; j+w[i+1] <=sum; j++) {
			
				dp[i + 1][j + w[i + 1]] = dp[i][j];
			
			
		}
	}
	if (dp[N - 1][sum]) {
		cout << "possible" << endl;
	}
	else {
		cout << "impossible" << endl;
	}
	return 0;

}