#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 pos[100*101] = {0};


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 {
        for (int i = 0; i < N; i++) {
            for (int j = 10000; j >= 0; j--) {
                if (pos[j]) pos[j+W[i]] = true;
            }
        }
        if (pos[half]) cout << PO << endl;
        else cout << IM << endl;
    }
}