//No.4 おもりと天秤

import java.util.*;
import java.io.*;
import static java.util.Arrays.*;
import static java.lang.Math.*;

public class No4 {
    
    static final Scanner sc = new Scanner(System.in);
    static final PrintWriter out = new PrintWriter(System.out,false);

    static void solve() {
        int n = sc.nextInt();
        int[] w = new int[n];
        int sum = 0;
        for (int i=0; i<n; i++) {
            w[i] = sc.nextInt();
            sum += w[i];
        }
        if (sum%2 == 1) {
            out.println("impossible");
            return;
        }

        boolean[][] dp = new boolean[n+1][sum/2+1];
        dp[0][0] = true;
        for (int i=0; i<n; i++) {
            for (int j=0; j<=sum/2; j++) {
                if (!dp[i][j]) continue;
                dp[i+1][j] = true;
                if (j + w[i] <= sum/2) dp[i+1][j + w[i]] = true;
            }
        }

        out.println(dp[n][sum/2]?"possible":"impossible");
    }

    public static void main(String[] args) {
        long start = System.currentTimeMillis();

        solve();
        out.flush();

        long end = System.currentTimeMillis();
        //trace(end-start + "ms");
        sc.close();
    }

    static void trace(Object... o) { System.out.println(deepToString(o));}
}