#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) FOR(i,0,n)
#define repr(i,n) for(int i=(n)-1;0<=i;--i)
#define each(e,v) for(auto&& e:(v))
#define all(v) begin(v),end(v)
#define DUMP(x) cerr<<#x<<": "<<(x)<<endl
#define DEBUG(x) cerr<<#x<<": "<<(x)<<" (L"<<__LINE__<<")"<<endl
using namespace std;
using vint = vector<int>;
using vdouble = vector<double>;
using vstring = vector<string>;
using ll = long long;
template <class T> void chmin(T& a, const T& b) { a = min(a, b); }
template <class T> void chmax(T& a, const T& b) { a = max(a, b); }

int main() {
    int N; cin >> N;
    vint w(N);
    rep(i, N) cin >> w[i];
    sort(all(w));
    const int W = accumulate(all(w), 0);
    if(W % 2 != 0) { cout << "impossible" << endl; return 0; }
    int dp[N+1][W+1];
    fill(dp[0], dp[N+1], 0);
    repr(i, N) {
        rep(mw, W+1) {
            if(mw < w[i]) dp[i][mw] = dp[i+1][mw];
            else dp[i][mw] = max(dp[i+1][mw], dp[i+1][mw - w[i]] + w[i]);
        }
    }
    if(dp[0][W/2] == W/2) cout << "possible" << endl;
    else cout << "impossible" << endl;
    return 0;
}