#include <iostream>
#include <vector>
using namespace std;
int main() {
  int N;
  cin >> N;
  vector<int> W(N);
  int sum = 0;
  for(int i = 0; i < N; i++) cin >> W[i];
  vector<int> dp(N * 101);
  dp[0] = 1;
  for(int i = 0; i < N; i++) {
    sum += W[i];
    for(int j = dp.size() - 1; j >= W[i]; j--) {
      if(dp[j - W[i]]) dp[j] = 1;
    }
  }
  cout << ((sum % 2 == 0 && dp[sum / 2]) ? "possible" : "impossible") << endl;
}