#include <iostream>
#include <vector>

using namespace std;

int main(void){
	int N; cin >> N;
	vector<int> W(N);
	int sum = 0;
	for(int &a:W){
		cin >> a;
		sum += a;
	}
	vector<bool> check(sum+1);
	if(sum%2 == 1){
		cout << "impossible" << endl;
		return 0;
	}

	check[0] = true;

	for(auto &a:W){
		for(int i=check.size()-1;i>=0;--i)	if(i-a >= 0 && check[i-a]) check[i] = true;
	}
	if(check[sum/2]) cout << "possible" << endl;
	else cout << "impossible" << endl;
}