#include<iostream>
#include<algorithm>


using namespace std;


bool dp[10000];

int main(){
	int N,w[100];
	int sum = 0;
	cin >>N;
	for (int i=0; i < N; i++){
		cin >> w[i];
		sum += w[i];
	}
	if(sum%2 ==1){
		cout << "impossible" <<endl;
		return 0;
	}

	int m = sum/2;
	dp[0] = true;
	for(int i=0; i < N; i++){
		for(int j = m; j>=w[i];j--){
			dp[j] = dp[j] | dp[j-w[i]];
		}
	}

	if(dp[m])
		cout<< "possible" << endl;
	else
		cout << "impossible" << endl;
	return 0;
}