import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Here your code !
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] W = new int[100];
        boolean[][] dp = new boolean[101][10001];
        int sum = 0;
        
        for(int i=0; i<101; i++)
            for(int j=0; j<10001; j++)
                dp[i][j] = false;
        
        for(int i=0; i<N; i++){
            W[i] = sc.nextInt();
            sum += W[i];
        }
        
        if(sum%2 == 1) System.out.println("impossible ");
        else{
            dp[0][0] = true;
            for(int i=0; i<N; i++){
                for(int j=0; j<=10000; j++){
                    if(dp[i][j] == true){
                        dp[i+1][j+W[i]] = true;
                        dp[i+1][j] = true;
                    }
                }
            }
            
            if(dp[N][sum/2] == true) System.out.println("possible");
            else System.out.println("impossible ");
        }
    }
}