#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define EPS (1e-7)
#define INF (1e9)
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define all(x) x.begin(),x.end()
const double PI = acos(-1);
const ll MOD = 1000000007;
template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}
 
template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}
///////////////////////////////////////////////////////////////
bool A[101][21000];
int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int N; cin >> N;
    vector<int> W(N);
    rep(i,N) cin >> W[i];

    A[0][10100] = true;
    rep(i,N) {
        rep(j,21000) {
            if (j >= W[i] && A[i][j]) A[i+1][j-W[i]] = true;
            if (j < 21000 - W[i] && A[i][j]) A[i+1][j+W[i]] = true;
        }
    }

    cout << (A[N][10100] ? "possible" : "impossible ") << endl;
}