#include<iostream>
#include<map>
using namespace std;
int N,SUM=0;
int max(int a,int b){
    if(a>b)
        return a;
    else
        return b;
}
int search(int n,int s,int *w){
    if(n!=N-1)
        return max(search(n+1,s,w),search(n+1,s+w[n],w));
    else if(s==SUM/2)
        return 1;
    else
        return 0;
}
int main(){
    int i;
    cin>>N;
    int w[N];
    for(i=0;i<N;i++){
        cin>>w[i];
        SUM+=w[i];
    }
    if(SUM%2==1)
        cout<<"impossible"<<endl;
    else if(max(search(0,0,&w[0]),search(0,w[0],&w[0]))==1)
        cout<<"possible"<<endl;
    else
        cout<<"impossible"<<endl;
    return 0;
}