#define ll long long
#define ffor(i,a,b) for (int i=(a);i<(b);i++)
#define rfor(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define rep(i,n) for (int i=0;i<(n);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<cmath>
#include<string>
#include<stack>
#include<queue>
#include<vector>
#include<map>
#define SIZE 100001
#define MOD 1000000007
#define INF 100000000
using namespace std;

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	int n;
	cin >> n;
	int v[100];
	rep(i,n) cin >> v[i];

	sort(v,v+n);
	int a = v[n-1];
	int b = 0;
	for(int i=n-2; 0<=i;i--){
		if(a<b) a += v[i];
		else b += v[i];
	}

	cout << ((a==b)?"possible":"impossible") << endl;
	return 0;
}