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

int main(){
  int N;
  cin >> N;
  vector<int> W(N);
  int S = 0;
  for(int i=0;i<N;i++){
    cin >> W[i];
    S += W[i];
  }
  if(S%2 == 1)  cout << "impossible" << endl;
  else{
    S /= 2;
    vector<vector<bool>> dp(N+1,vector<bool>(S+1,false));
    dp[0][0] = true;
    for(int i=1;i<=N;i++){
      for(int j=0;j<=S;j++){
        if(dp[i-1][j]){
          dp[i][j] = true;
        }
        if(j-W[i-1] >= 0){
          if(dp[i-1][j-W[i-1]]){
            dp[i][j] = true;
          }
        }
      }
    }
    if(dp[N][S]) cout << "possible" << endl;
    else cout << "impossible" << endl;
  }
}