#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;

const ld pi = 3.14159265358979;
const int mod = 1000000007;

int main(){
	int n;
	cin >> n;
	vector<int> a(n);
	int sum = 0;
	for(int i = 0; i < n; i++){
		cin >> a[i];
		sum += a[i];
	}
	
	if(sum % 2 == 1){
		cout << "impossible" << endl;
		exit(0);
	}

	vector<int> dp(30000 , 0);
	dp[0] = 1;
	for(int i = 0; i < n; i++){
		vector<int> dp2;
		dp2 = dp;
		for(int j = 0; j < 20000; j++){
			if(dp[j] == 1)dp2[j + a[i]] = 1;
		}
		dp = dp2;
	}
	if(dp[sum / 2] == 1){
		cout << "possible" << endl;
	}else{
		cout << "impossible" << endl;
	}
	return 0;
}