#include <iostream>
using namespace std;

#define fastcin {\
    cin.tie(0);\
    ios::sync_with_stdio(false);\
}
#define scan(x) cin >> x
#define print(x) cout << x << "\n"


int main() {
    fastcin;

    int n, i, j;
    scan(n);
    int sum = 0, w[n];
    for (i = 0; i < n; ++i) {
        scan(w[i]);
        sum += w[i];
    }

    if ((sum & 0x01)) {
        print("impossible");
        return 0;
    } else {
        int half = sum/2;
        bool dp[n+1][half+1];
        for (i = 0; i < n+1; ++i) for (j = 0; j < half+1; ++j) dp[i][j] = false;
        dp[0][0] = true;

        for (i = 0; i < n; ++i) {
            for (j = 0; j < half+1; ++j) {
                dp[i+1][j] |= dp[i][j];
                if (j+w[i] <= half) dp[i+1][j+w[i]] |= dp[i][j];
            }
            if (dp[n][half]) {
                print("possible");
                return 0;
            }
        }
        print("impossible");
        return 0;
    }
}