#include <bits/stdc++.h>
using namespace std;


int main() {
    int n;
    cin>>n;
    vector<int> w(n);
    int sum=0;
    for(int i=0; i<n; i++){
        cin>>w[i];
        sum+=w[i];
    }

    if(sum%2){
        cout << "impossible" << endl;
        return 0;
    }

    vector<vector<int>> dp(n+1, vector<int>(sum+1));
    dp[0][0]=1;
    for(int i=0; i<n; i++){
        for(int j=0; j<=sum; j++){            
            if(j+w[i]<n*100+1){
                dp[i+1][j+w[i]] += dp[i][j];
            }

            dp[i+1][j] = max(dp[i+1][j], dp[i][j]);
        }
    }

    cout << (dp[n][sum/2] ? "possible" : "impossible") << endl;
    return 0;
}