#define _CRT_SECURE_NO_WARNINGS
//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(ll i=a; i<ll(b); i++)
#define rep(i,b) loop(i,0,b)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
template<class T> istream& operator>>(istream& is, vector<T>& v);
template<class T> ostream& operator<<(ostream& os, vector<T> const& v);
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream&, const tuple<T...>&){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream& os, const tuple<T...>& t){ os << (n==0?"":" ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream& operator<<(ostream& os, const tuple<T...>& t){ _ot<0>(os, t); return os; }
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _it(istream&, tuple<T...>&){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _it(istream& is, tuple<T...>& t){ is >> get<n>(t); _it<n+1>(is, t); }
template<class...T> istream& operator>>(istream& is, tuple<T...>& t){ _it<0>(is, t); return is; }
template<class T> istream& operator>>(istream& is, vector<T>& v){ rep(i,v.size()) is >> v[i]; return is; }
template<class T> ostream& operator<<(ostream& os, vector<T> const& v){ rep(i,v.size()) os << v[i] << (i+1==(int)v.size()?"":" "); return os; }
#ifdef DEBUG
#define dump(...) (cerr<<#__VA_ARGS__<<" = "<<mt(__VA_ARGS__)<<" ["<<__LINE__<<"]"<<endl)
#else
#define dump(...)
#endif

int main(){
    int N;
    while(cin>>N){
        vi v(N); cin >> v;
        int t = accumulate(all(v),0);
        vi dp(t+1);
        dp[0] = 1;
        rep(i,N){
            for(int j=t; j>=v[i]; j--) dp[j] |= dp[j-v[i]];
        }
        puts(t%2==0 && dp[t/2] ? "possible" : "impossible");
    }
}