#include <bits/stdc++.h>
using namespace std;
#define REP(i,N) for(i=0;i<N;i++)
typedef long long ll;
typedef pair<int, int> P;
typedef struct{
  int first;
  int second;
  int third;
}T;

//昇順
bool comp_Se(T& l, T& r){
  return l.second < r.second;
}

int main(void){
  int N;
  cin >> N;
  vector<int> W(N);
  int i,j,sum=0;
  REP(i,N){
    cin >> W[i];
    sum+=W[i];
  }
  if(sum%2){
    cout << "impossible" << endl;
    return 0;
  }
  sum/=2;
  //dp[j] 重さjにすることが可能
  vector<bool> dp(sum+1,false);
  dp[0] = true;
  REP(i,N){
    for(j=sum-1;j>=0;j--){
      if(W[i]+j>sum)continue;
      if(dp[j]){
        dp[j+W[i]] = true;
      }
    }
  }
  if(dp[sum]) cout << "possible" << endl;
  else cout << "impossible" << endl;
  return 0;
}