#include <iostream>
#include <algorithm>
using namespace std;

int main()
{
    int n;
    while (cin>>n) {
        int s=0;
        vector<int> w(n);
        for(auto& v: w) { cin>>v; s+=v; }

        vector<int> d(s+1);
        d[0]=1;
        for(int i=0;i<n;++i) for(int j=s/2;j>=0;--j) if (d[j]) d[j+w[i]]=1;
        cout<<(s%2 or !d[s/2] ? "impossible" : "possible")<<endl;
    }
}