#include <iostream>
#include <vector>
#include <cmath>
#include <string>
#include <algorithm>
#include <iomanip>
#include <map>
#include <bitset>
#include <cstdio>
#include <set>
#include <stack>
#include <queue>
#include <cassert>
#include <numeric>
#define rep(i,n) Rep(i,0,n)
#define Rep(i,k,n) for(int i=k ; i<n ; i++)
#define rep1(i,n) for(int i=1 ; i<=n ; i++)
#define vi vector<int>
#define vii vector<vector<int>>
#define mii map<int,int>
#define Sort(v) sort(v.begin(),v.end())
#define Reverse(v) reverse(v.begin(),v.end())
#define ALL(a)  (a).begin(),(a).end()
#define pb push_back
#define mp make_pair
#define SP <<" "<<
//#define int ll

typedef long long ll;

const int md = 1000000007;
const int INF = 1<<30;
using namespace std;

int w[1000];

bool check(int n, int l, int r){
    if(l == r) return true;
    if(l < r) return false;
    if(n == 1) return false;
    
    //cout << n SP l SP r << endl;
    return (check(n-1, l-w[n-1] , r + w[n-1]) || check(n-1, l,r));

}

int main(){
    int n; cin >> n;
    
    int sum = 0;
    rep(i,n) {
        cin >> w[i];
        sum += w[i];
    }

    if(sum % 2 != 0){
        cout << "impossible" << endl;
        return 0;
    }

    bool ans = check(n,sum,0);

    if(ans) cout << "possible" << endl;
    else cout << "impossible" << endl;

    

}