#include <iostream>
#include <string>
#include <vector>
#include <stack>
#include <algorithm>
#include <numeric>

int main()
{
    int n = 0;
    std::cin >> n;

    bool found = false;

    std::vector< int > v;

    for( int i = 0; i < n; ++i )
       {
           int tmp;
           std::cin >> tmp;
           v.push_back(tmp);
       }

    std::sort(v.begin(), v.end());

    int sum = std::accumulate(v.begin(), v.end(), 0);
    int h = sum/2;

    if(sum % 2 == 0)
    for( auto it = v.rbegin(); it != v.rend(); ++it )
    {
        //std::cout << "it: " << *it << std::endl;
        if(sum - *it >= h )
        {
            sum -= *it;
        }
        else
        {
            sum -= *it;
            h -= *it;
        }
        //std::cout << "sum: " << sum << ", half:" << h << std::endl;
    }


    if( sum == 0 && h == 0 )
        found = true;
    
    if( found )
        std::cout << "possible" << std::endl;
    else
        std::cout << "impossible" << std::endl;

}