#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
#define max 1e18
#define FOR(i,l,r) for(ll i=l;i<r;i++)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,l,r) for(ll i=r-1;i>=l;i--)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define P pair<ll,ll>
#define F first
#define S second
#define BS(A,x) binary_search(ALL(A),x)
#define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin())
#define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin())
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
using mint=modint1000000007;
signed main(){
  ll n,s=0;cin>>n;vector<ll>w(n);REP(i,n)cin>>w[i];REP(i,n)s+=w[i];
  if(s%2){cout<<"impossible"<<endl;return 0;}vector<bool>dp(1e4+1,0);dp[0]=1;
  REP(i,n)RREP(j,1e4+1-w[i])if(dp[j])dp[j+w[i]]=1;
  if(dp[s/2])cout<<"possible"<<endl;else cout<<"impossible"<<endl;
  return 0;
}