#include <bits/stdc++.h>
using namespace std;

#define rep(i, j, n) for(int i=j;i<n;++i)
#define all(i) i.begin(),i.end()
#define rall(i) i.rbegin(),i.rend()
#define INF 1e9
const int mod = 1e9 + 7;

typedef long long i64;
typedef pair<int, int> pi;

template <class T> using vt = vector<T>;
template <class T> using vvt = vector<vector<T>>;

i64 gcd(i64 n, i64 m) {return (m == 0? n : gcd(m, n % m));}
i64 lcm(i64 n, i64 m) {return (n / gcd(n, m) * m);}
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n;
  cin >> n;
  vt<int> w(n);
  rep(i, 0, n) cin >> w[i];

  int sum = 0;
  rep(i, 0, n) sum += w[i];
  if(sum % 2) return cout << "impossible\n", 0;

  vvt<bool> dp(n + 1, vt<bool>(sum + 1, false));
  dp[0][0] = true;
  rep(i, 0, n) {
    rep(j, 0, sum + 1) {
      dp[i + 1][j] = dp[i][j];
      if(j >= w[i]) dp[i + 1][j] = (dp[i + 1][j] || dp[i][j - w[i]]);
    }
  }

  if(dp[n][sum / 2]) cout << "possible\n";
  else cout << "impossible\n";
}