#include <iostream>
#include <string>
#include <algorithm>
#include <queue>
#include <vector>
#include <cmath>
#include <cctype>
#define rep(i,a,b) for(int i=(a);i<b;i++)
#define INF 1000000000
using namespace std;
bool debug=false;
int sum=0;
int dp[101][10001];
int n,w[100];

void solve(){
  dp[0][0]=true;
  for(int i=0;i<n;i++){
    for(int j=0;j<10001;j++){
      if(dp[i][j]){
	dp[i+1][j+w[i]]=true;
	dp[i+1][j]=true;
      }
    }
  }
  if(debug){
    for(int i=0;i<10;i++){
      for(int j=0;j<10;j++){
	cout<<" "<<dp[i][j];
      }
      cout<<endl;
    }
  }
  if(dp[n-1][sum/2])cout<<"possible"<<endl;
  else cout<<"impossible"<<endl;
}

int main(){
  cin>>n;
    rep(i,0,n){
    cin>>w[i];
    sum+=w[i];
  }
    if(sum%2==1){
    cout<<"impossible"<<endl;
    return 0;
  }

  rep(i,0,n)rep(j,0,10001)dp[i][j]=false;
  solve();
  return 0;
}