#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
signed main(){
  using BS = bitset<30000>;
  Int n;
  cin>>n;
  vector<Int> w(n);
  for(Int i=0;i<n;i++) cin>>w[i];
  BS dp(0);
  dp[0]=1;
  for(Int i=0;i<n;i++) dp=dp|(dp<<w[i]);

  Int s=0;
  for(Int i=0;i<n;i++) s+=w[i];

  cout<<(s%2==0&&dp[s/2]?"possible":"impossible")<<endl;
  return 0;
}