#include <bits/stdc++.h>

using i64 = long long;

int main() {

    std::cin.tie(nullptr)->sync_with_stdio(false);

    int n;
    std::cin >> n;

    std::vector<i64> a(n);

    for (auto &x : a) std::cin >> x;

    auto s = std::accumulate(a.begin(), a.end(), 0LL);

    if (s & 1) {
        std::cout << "impossible\n";
        return 0;
    }

    s >>= 1;

    std::vector<i64> dp(s + 1);

    dp[0] = 1;

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j <= s; ++j) {
            if (dp[j] && j + a[i] <= s) {
                dp[j + a[i]] = 1;
            }
        }
    }
    
    std::cout << (dp[s] ? "possible" : "impossible") << '\n';

    return 0;
}