import java.util.Scanner;

public class No4 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		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 != 0) {
			System.out.println("impossible");
			return;
		}
		int sum = Sum/2;
		int dp[][] = new int[N+1][sum+1];
		
		for(int i = 1;i < N+1;i++) {
			for(int j = 1;j < sum+1;j++) {
				if(j >= w[i-1]) {
					dp[i][j] = Math.max(dp[i-1][j-w[i-1]] + w[i-1], dp[i][j-1]);
				}else {
					dp[i][j] = dp[i][j-1];
				}
			}
		}
		
		if(dp[N][sum] == sum) {
			System.out.println("possible");
		}else {
			System.out.println("impossible");
		}
	}
}