#include <iostream>

int main()
{
    int N;
    int W[101];
    std::cin >> N;
    int sum = 0;
    for(int i = 0;i < N;i++)
    {   
        std::cin >> W[i];
        sum += W[i];
    }
    int tmpW;
    int sumA = 0, sumB = 0;
    for(int i = 0; i < N - 1;i++)
    {
        for(int j = i + 1;j < N;j++)
        {
            if(W[i] < W[j])
            {
                tmpW = W[i];
                W[i] = W[j];
                W[j] = tmpW;
            }
        }
    }
    for(int i = 0; i < N;i++)
    {
        if(sumA <= sumB)
        {
            if(sumA < sum / 2 && sumA + W[i] <= sum / 2)
            {
                sumA += W[i];
            }
            else
            {
                sumB += W[i];
            }
        }
        else
        {
            if(sumB < sum / 2 && sumB + W[i] <= sum / 2)
            {
                sumB += W[i];
            }
            else
            {
                sumA += W[i];
            }
        }
    }
    if(sumA != sumB)
    {
        std::cout << "impossible" << std::endl;
    }
    else
    {
        std::cout << "possible" << std::endl;
    }
    
    return 0;
}