#include<iostream>
#include<vector>
typedef long long ll;
using namespace std;
int main() {
	ll N;
	cin >> N;
	vector<ll>a(N);
  	ll sum=0;
	for (ll i = 0; i < N; i++) {
		cin >> a[i];
      	sum+=a[i];
	}
	ll dp[10001];
	for (ll i = 0; i <=10000; i++) {
		dp[i] = 0;
	}
  	dp[0]=1;
	for (ll i = 0; i < N; i++) {
		for (ll j = 10000; j >= 0; j--) {
			if (dp[j]&&a[i] + j <= 10000)
              dp[j + a[i]] =1;
			}
    }
  	ll x;
  	string ans="impossible";
	for (ll i = 0; i <=10000; i++) {
		if (dp[i])
          x=i;
      	if(sum==2*x){
          ans="possible";
          break;
        }
    }
      cout<<ans<<endl;
}