#include<iostream>
#include<algorithm>

#define DEBUG
#define NMAX 100

using namespace std;

int main(){
    int N;
    int W[NMAX];
    int sum;

    cin>>N;
    for(int i=0;i<N;i++){
        cin>>W[i];
    }

    sum=0;
    for(int i=0;i<N;i++){
        sum+=W[i];
    }

    if(sum%2==1) cout<<"impossible"<<endl;
    else{
        sort(W,W+N);
        for(int i=0;i<N;i++){
            sum-=W[i];
            if(sum==0){
                cout<<"possible"<<endl;
                break;
            }
            if(sum<0){
                cout<<"impossible"<<endl;
                break;
            }
        }
    }
}