#include <bits/stdc++.h>
#include <iostream>
#include<math.h>
using namespace std;
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
vector<int>vec;
vector<vector<int>>dp;
int avg;
int N;
int dfs(int i, int now) {
    if (dp[i][now] != -1) return dp[i][now];

    if (i == 0) {
        if (now == 0) return 1;
        return 0;
    }

    int res = 0;
    int n = vec[i-1];
    if (now >= n && dfs(i-1, now-n) == 1) res = 1;
    if (dfs(i-1, now) == 1) res = 1;


    return dp[i][now] = res;
}
int main()
{
    cin >> N;
    vec.resize(N);
    int sum = 0;
    for (int i=0; i<N; i++) {
        cin >> vec.at(i);
        sum += vec[i];
    }

    avg = sum/2;
    dp.assign(N+1, vector<int>(avg+1, -1));
    if (sum % 2 != 0) {
        cout << "impossible" << endl;
    } else {
        if (dfs(N, avg) == 1) {
            cout << "possible" << endl;
        } else {
            cout << "impossible" << endl;
        }
    }
    return 0;
}