import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
    static int ans = 1, index=0;
	public static class Node{
      int val;
      Node left;
      Node right;
      Node(int val) {
        this.val = val;
        this.left = null;
        this.right = null;
      }
    }

   public static Node insert(Node root, int val){
     if(root == null) {
       return new Node(val);
     }

     if(val < root.val){
       root.left = insert(root.left, val);
     }
     else
       root.right = insert(root.right, val);

     return root;
   }

    public static void inOrderTraversal(Node root , int[] arr){
      if(root == null) {
        return;
      }

      inOrderTraversal(root.left, arr);

      if(root.val != arr[index]){
        ans = 0;
      }
      index+=1;
      inOrderTraversal(root.right, arr);

    }
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
        int size = in.nextInt();

        int arr[] = new int[size];

        for(int i = 0; i < size; i++) {
          arr[i] = in.nextInt();
        }

        Node root = null;
        root = new Node(arr[0]);

        for(int i = 1; i < size; i++) {
          root = insert(root, arr[i]);
        }

        inOrderTraversal(root, arr);

        System.out.print(ans);
  }
}