package yukicoder;
import java.util.*;

public class P4 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int sum = 0;
		int[] W = new int[N];
		for(int i=0; i<N; i++) {
			W[i] = sc.nextInt();
			sum += W[i];
		}
		if(sum%2==1) {
			System.out.println("impossible");
			return;
		}
		boolean[][] possible = new boolean[N+1][sum+1];
		for(int i=0; i<N+1; i++) {
			Arrays.fill(possible[i], false);
		}
		possible[0][0] = true;
		for(int i=0; i<N; i++) {
			for(int w=0; w<=sum; w++) {
				if(w-W[i]>=0&&possible[i][w-W[i]]) {
					possible[i+1][w] = true;
				} else {
					possible[i+1][w] = possible[i][w];
				}
			}
		}
		if(possible[N][sum/2]) {
			System.out.println("possible");
		} else {
			System.out.println("impossible");
		}
		
	}

}