#include<cstdio>
#include <iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>

#define mod 1000000007;

using namespace std;
typedef long long ll;
typedef pair<ll, ll> Pr;

int N,k;
int w[110];

bool dfs(int i, int sum) {
	if (i == N)return sum == k;
	if (dfs(i + 1, sum))return true;
	if (dfs(i + 1, sum + w[i]))return true;
	return false;
}

int main()
{
	cin >> N;

	ll sum = 0;
	for (int i = 0; i < N; i++) {
		cin >> w[i];
		sum += w[i];
	}

	k = sum / 2;
	if (sum % 2 != 0) {
		cout << "impossible" << endl;
		return 0;
	}

	if (dfs(0, 0))cout << "possible" << endl;
	else cout << "impossible" << endl;
	return 0;
}