#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> P;
typedef pair<ll,ll> l_l;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
const int INF=1001001000;
const int mINF=-1001001000;
const ll LINF=1010010010010010000;
template<class T> inline bool chmin(T& a, T b) {
if (a > b) {
a = b;
return true;
}
return false;
}
template<class T> inline bool chmax(T& a, T b) {
if (a < b) {
a = b;
return true;
}
return false;
}
//グリッド：（典型）dp,dfs,bfs,最短経路,その他
ll dp[110][5010];
int main(){
    int n;cin >> n;
    vl w(n);
    rep(i,n) cin >> w[i];
    rep(i,110){
        rep(j,5010){
            dp[i][j]=INF;
        }
    }
    dp[0][0]=0;
    rrep(i,n){
        rep(j,5001){
            if(j-w[i-1]>=0){
                if(dp[i-1][j-w[i-1]]!=INF){
                    dp[i][j]=dp[i-1][j-w[i-1]];
                }
            }
            if(dp[i-1][j]!=INF) dp[i][j]=dp[i-1][j]+w[i-1];
        }
    }
    //cout << dp[1][1] << endl;
    rep(j,5001){
        if(j==dp[n][j]){
            cout << "possible" << endl;
            return 0;
        } 
    }
    cout << "impossible" << endl;
    return 0;
}