#include <iostream>
#include <vector>
#include <numeric>
using namespace std;
#define REP(i, N) for(int i=0;i<(N);++i)

int main() {
    int n; cin >> n;
    vector<int> ws(n); REP(i, n) cin >> ws[i];
    int sum = accumulate(ws.begin(), ws.end(), 0);
    if (sum % 2 == 1) {
        cout << "impossible" << endl;
        return 0;
    }

    int half = sum / 2;
    vector<bool> memo(10000, false);
    memo[0] = true;
    for (int w : ws) {
        for (int i = half; i >= 0; --i) if(memo[i]) memo[i+w] = true;
    }

    if (memo[half]) {
        cout << "possible" << endl;
    } else {
        cout << "impossible" << endl;
    }
}