#include<bits/stdc++.h>
#define rep(i,a,n) for (int i = a;i < n;i++)
#define per(i,n,a) for (int i = n-1;i >= a;i--)
using namespace std;

#define MAX 100000
bool dp[MAX];
int main(){
    int n; cin >> n;
    vector<int> w(n);
    int sum = 0;
    rep(i,0,n){
        cin >> w[i];
        sum += w[i];
    }
    dp[0] = true;
    rep(i,0,n){
        per(j,MAX-w[i],0){
            dp[j+w[i]] |= dp[j];
        }
    }
    if (sum % 2 == 1 || !dp[sum / 2]){
        cout << "impossible" << endl;
    } else {
        cout << "possible" << endl;
    }
}