#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)

int main() {
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	
	int N;
	cin >> N;
	vector<int> W(N);
	int sum = 0;
	rep(i, 0, N) {
		cin >> W[i];
		sum += W[i];
	}
	
	if (sum % 2 == 1) {
		cout << "impossible\n";
		return 0;
	}
	
	int maxi = 10100;
	vector<bool> dp(maxi, false);
	dp[0] = true;
	dp[W[0]] = true;
	
	rep(i, 1, N) {
		for (int j = maxi - 1; j >= 0; --j) {
			if (dp[j] && j + W[i] < maxi) dp[j + W[i]] = true;
		}
	}
	
	cout << (dp[sum/2] ? "possible\n" : "impossible\n");
}