import java.util.Arrays;
import java.util.Scanner;

public class Main4 {
	public static void main(String[] args) {
		Main4 p = new Main4();
	}

	public Main4() {
		Scanner sc = new Scanner(System.in);
		int n =sc.nextInt();
		int[] w =new int[n];
		for(int i=0;i<n;i++)
			w[i] = sc.nextInt();
		solve(n, w);
	}

	public void solve(int n, int[] w) {
		Arrays.sort(w);
		boolean[] dp = new boolean[w[n-1]*w[n-1]+1];
		
		dp[0] = true;
		for(int i=0;i<w.length;i++){
			for(int j=dp.length-1;j>=0;j--){
				if(j-w[i] >= 0 && dp[j-w[i]]){
					dp[j] = true;
				}
			}
		}
		
		int sum = 0;
		for(int i=0;i<w.length;i++)
			sum += w[i];
		if(sum%2==0 && dp[sum/2])
			System.out.println("possible");
		else
			System.out.println("impossible");
		
	}

}