#include <iostream>

#define rep(i,a,b) for(int i=(a);i<(b);i++)
using namespace std;

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

	int dp[10001] = {};
	dp[0] = 1;
	rep(i,0,n) {
		for(int j = 10000; j >= 0; j--) {
			if(dp[j]) dp[j + w[i]] = 1;
		}
	}

	dp[sum/2]? cout << "possible" << endl : cout << "impossible" << endl;

	return 0;
}