#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int (i)=(0);(i)<(int)(n);++(i))
using ll = long long;
using P = pair<int, int>;
using namespace std;

template<class T> void vin(vector<T>& v, int n) {
    v.resize(n);
    for (int i = 0; i < n; ++i) {
        cin >> v[i];
    }
}

string pos = "possible", imp = "impossible";
int dp[101][101][101];
int N;
int W[101];

int solve(int idx, int l, int r) {
    int& res = dp[idx][l][r];
    if (~res) return res;
    if (idx >= N) {
        res = (l == r);
    }
    else {
        res = max(solve(idx+1, l+W[idx], r), solve(idx+1, l, r+W[idx]));
    }
    return res;
}

int main() {
    cin >> N;
    rep(i, N) cin >> W[i];
    rep(i, 101) rep(j, 101) rep(k, 101) dp[i][j][k] = -1;
    cout << (solve(0, 0, 0) == 1 ? pos : imp) << endl;
    return 0;
}