#include <iostream>
#include <algorithm>
#include <vector>
#include <stdio.h>
#include <cmath>

using namespace std;
typedef uint uint32_t;

#define IM "impossible"
#define PO "possible"
int N;
int W[100];
int half = 0;

bool req(int idx, int w) {
    if (idx == N) return w == half;
    return req(idx+1, w+W[idx]) || req(idx+1, w);
}

int main() {
    cin >> N;
    for (int i = 0; i < N; i++) {
        cin >> W[i];
        half += W[i];
    }
    if (half % 2 != 0) cout << IM << endl;
    else {
        half /= 2;
        cout << (req(0, 0)?PO:IM) << endl;
    }
}