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

bool dp[105][5005];

int main(){
  int n; cin >> n;
  vector<int> w(n);
  for(int i = 0; i < n; i++) cin >> w[i];
  int sum = 0;
  for(int i = 0; i < n; i++) sum += w[i];
  if(sum%2==1){
    cout << "impossible" << endl;
    return 0;
  }
  int sum2 = sum / 2;
  dp[0][0] = true;
  for(int i = 0; i < n; i++){
    for(int j = 0; j <= sum2; j++){
      if(j-w[i]>=0) dp[i+1][j] |= dp[i][j-w[i]]|dp[i][j];
      else dp[i+1][j] |= dp[i][j];
    }
  }
  if(dp[n][sum2]) cout << "possible" << endl;
  else cout << "impossible" << endl;
  return 0;
}