#include<iostream>
#include<vector>
using namespace std;
int main(){
	int n, sum = 0;
	cin >> n;
	vector<int>v(n);
	for (int i = 0; i < n; i++) cin >> v[i], sum += v[i];
	if (sum % 2){
		cout << ("impossible") << endl; return 0;
	}
	vector<int>dp(sum + 1);
	dp[0] = 1;
	for (int i = 0; i < n; i++){
		for (int j = sum; j >= v[i]; j--){
			dp[j] |= dp[j - v[i]];
		}
	}
	cout << (dp[sum / 2] ? "possible" : "impossible") << endl;
	return 0;
}