#include <iostream>
#include <cstdio>
#include <algorithm>

using namespace std;


int n;
int w[110];
int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>w[i];
    }
    int ans1=0,ans2=0;
    sort(w,w+n);
    for(int i=n-1;i>=0;i--){
        if(ans1>ans2){
            ans2+=w[i];
        }
        else ans1+=w[i];
    }
    //cout<<ans1<<" "<<ans2<<endl;
    if(ans2==ans1)cout<<"possible"<<endl;
    else cout<<"impossible"<<endl;
}