#include <bits/stdc++.h>

using namespace std;

int N;
int W[101];

bool memo[100][10001];

int rec(int i, int j, int k)
{
    if (i == N) return j == k;

    if (memo[i][j]) return false;

    memo[i][j] = true;

    if (rec(i + 1, j + W[i], k)) return true;
    if (rec(i + 1, j, k + W[i])) return true;

    return false;
}

int main()
{
    cin >> N;
    for (int i = 0; i < N; i++) cin >> W[i];
    cout << (rec(0, 0, 0) ? "possible" : "impossible") << endl;
}