#include <iostream>
using namespace std;
int main(){
        int N,w[100],sum=0;
        cin >> N;
        for(int i=0 ; i<N ; i++ ){
                cin >> w[i];
                sum+=w[i];
        }
        if(sum%2){
                cout<<"impossible"<<endl;
                return 0;
        }
        bool dp[101][10000];
        for(int i=0 ; i<=100 ; i++ )
                dp[i][0]=1;
        for(int i=1 ; i<=N ; i++ ){
//              cout <<endl<<w[i-1] << endl;
                for(int j=1 ; j<sum ; j++ ){
                        if(w[i-1]>j)
                                dp[i][j]=dp[i-1][j];
                        else
                                dp[i][j]=dp[i-1][j-w[i-1]]|dp[i-1][j];
                }
        }
        if(dp[N][sum/2])
                cout<<"possible"<<endl;
        else cout<<"impossible"<<endl;
        return 0;
}