#include <bits/stdc++.h>

using namespace std;

int N;
int W[110];
bool dp[10010];
int sum = 0;

int main() {
  cin >> N;
  for (int i = 0; i < N; i++) {
    cin >> W[i];
    sum += W[i];
  }

  if (sum & 1) {
    cout << "impossible\n";
  } else {
    sum >>= 1;
    dp[0] = true;
    for (int i = 0; i < N; i++) {
      for (int j = sum; j >= 0; j--) {
        if (j - W[i] < 0) continue;
        dp[j] |= dp[j - W[i]];
      }
    }
    cout << (dp[sum] ? "possible" : "impossible") << endl;
  }

  return 0;
}