#include<bits/stdc++.h>
using namespace std;
typedef long long int64;
const int INF = 1 << 30;

int main(){
  int N, W[100];
  bool dp[101][10001] = {};
  cin >> N;
  for(int i = 0; i < N; i++){
    cin >> W[i];
  }
  dp[0][0] = true;
  for(int i = 0; i < N; i++){
    for(int j = 10000; j >= 0; j--){
      if(j - W[i] >= 0) dp[i + 1][j - W[i]] |= dp[i][j];
      dp[i + 1][j + W[i]] |= dp[i][j];
    }
  }
  if(dp[N][0]) cout << "possible" << endl;
  else cout << "impossible" << endl;
}