#include <bits/stdc++.h>

int main() {
    int n;
    std::cin >> n;
    std::vector<int> w(n);
    int t = 0;
    for (int i = 0; i < n; i++) {
        std::cin >> w[i];
        t += w[i];
    }
    if (t % 2) {
        std::cout << "impossible" << std::endl;
        return 0;
    }
    t /= 2;
    std::bitset<5050> b;
    for (int i = 0; i < n; i++) {
        b = b | (b << w[i]);
        b[w[i]] = true;
    }
    std::cout << (b[t] ? "possible" : "impossible") << std::endl;

    return 0;
}