#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> P;
typedef pair<int,pair<int,int>> PP;
typedef long long ll;

const double EPS = 1e-9;
const int INF = 1e9;
const int MOD = 1e9+7;

int dy[] = {0,1,0,-1};
int dx[] = {1,0,-1,0};

int main(void) {
	int n;
	cin >> n;
	vector<int> w(n);
	for(int i=0;i<n;i++){
		cin >> w[i];
	}
	int sum = 0;
	for(int i=0;i<n;i++){
		sum += w[i];
	}
	if(sum%2 != 0){
		cout << "impossible" << endl;
		return 0;
	}

	sort(begin(w),end(w));
	
	vector<bool> dp(10001,false);
	dp[0] = true;
	for(int i=0;i<n;i++){
		for(int j=10000;j>=0;j--){
			if(dp[j])dp[j+w[i]] = true;
		}
	}
	if(dp[sum/2])cout << "possible" << endl;
	else cout << "impossible" << endl;


	return 0;
}