#include <iostream>
#include <vector>
using namespace std;
int n;
vector<int> w;
bool memo[100][10005] = {0};
bool solve(int i, int wi, int wj)
{
    if(i >= n)
        return wi == wj;
    if(memo[i][wi])
        return false;
    memo[i][wi] = true;
    if(solve(i + 1, wi + w[i], wj))
        return true;
    if(solve(i + 1, wi, wj + w[i]))
        return true;
    return false;
}
int main(void)
{
    cin >> n;
    w.resize(n);
    for(int i = 0; i < n; i++)
        cin >> w[i];
    if(solve(0, 0, 0))
        cout << "possible" << endl;
    else
        cout << "impossible" << endl;
    return 0;
}