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

// The main method must be in a class named "Main".
class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        int[] arr=new int[n];
        int count=0;
        for(int i=0;i<n;i++){
            arr[i]=sc.nextInt();
        }
        for(int i=1;i<n-1;i++){
            if(arr[i]>arr[i-1] && arr[i]>arr[i+1]){
                count++;
            }
        }
        System.out.println(count);
    }
}