#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;

const ld pi = 3.14159265358979;
const int mod = 1000000007;

int main(){
	int n;
	cin >> n;
	vector<int> a(n);
	int sum = 0;
	for(int i = 0; i < n; i++){
		cin >> a[i];
		sum += a[i];
	}
	
	if(sum % 2 == 1){
		cout << "impossible" << endl;
		exit(0);
	}

	sort(a.begin() , a.end());

	vector<int> dp(sum + 110 , 0);
	dp[0] = 1;
	for(int i = 0; i < n; i++){
		if(a[i] == 1){
			dp[1] = 1;
			continue;
		}
		for(int j = 0; j < dp.size(); j++){
			if(dp[j] == 1 && j + a[i] < dp.size())dp[j + a[i]] = 1;
			if(dp[sum / 2] == 1){
				cout << "possible" << endl;
				exit(0);
			}
		}
	}
	cout << "impossible" << endl;
	return 0;
}