#include <bits/stdc++.h>
#define rep(i,n) for(int i=(0);i<(n);i++)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	int n;
	cin >> n;

	int sm = 0;
	vector<int> w(n);
	rep(i, n) {
		cin >> w[i];
		sm += w[i];
	}

	if(sm % 2 == 1){
		cout << "impossible" << endl;
		exit(0);
	}

	int max_w = 10101;
	bool dp[2][max_w];
	rep(i, 2) rep(j, max_w) dp[i][j] = false;
	dp[0][0] = true;
	
	rep(i, n) {
		rep(j, max_w) dp[(i+1)%2][j] = false;

		rep(j, max_w){
			dp[(i+1)%2][j] |= dp[i%2][j];
			if(j-w[i] >= 0) dp[(i+1)%2][j] |= dp[i%2][j-w[i]];
		}
	}

	if(dp[n%2][sm/2]){
		cout << "possible" << endl;
	}else{
		cout << "impossible" << endl;
	}
}