#include<bits/stdc++.h>
using namespace std;
using ll=long long;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll n;cin>>n;
    vector<ll>w(n);
    ll sum=0;
    for(auto&o:w)
    {
        cin>>o;
        sum+=o;
    }
    if(sum%2!=0)
    {
        cout<<"impossible"<<endl;
        return 0;
    }
    vector<bool>dp(sum+9);
    dp[0]=true;
    for(int i=0;i<n;i++)
    {
        vector<bool>ndp=dp;
        for(int j=0;j<=sum;j++)
        {
            if(!dp[j]||j+w[i]>sum)continue;
            ndp[j+w[i]]=true;
        }
        swap(dp,ndp);
    }
    if(dp[sum/2])cout<<"possible"<<endl;
    else cout<<"impossible"<<endl;
}