#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);

    int N; cin >> N;
    vector<int> W(N);
    int s = 0;
    rep(i,N){
        cin >> W[i];
        s += W[i];
    }
    if(s&1){
        cout << "impossible" << endl;
        return 0;
    }

    s /= 2;

    vector<vector<bool>> dp(N+1,vector<bool>(10101,false));
    dp[0][0] = true;
    rep(i,N)for(int j=10101;j>=0;j--){
        if(dp[i][j]) dp[i+1][j+W[i]] = true;
    }

    bool ok = false;
    rep(i,N) if(dp[i][s]) ok = true;
    cout << (ok?"possible":"impossible") << endl;
}