using System;


namespace _04largerThanNeighbour
{
    class Larger
    {

        static int LargerThanNeighbour(int [] array)
        {
            int elements = 0;
            for (int i = 0; i < array.Length - 1; i++)
            {

                    if (array[i] > array[i + 1]&&array[i]>array[i-1])
                    {
                        elements++;
                    }



            }
            return elements;
        }
        static void Main()
        {
            int size = int.Parse(Console.ReadLine());
            var line = Console.ReadLine().Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
            int [] array = new int [size];
            for (int i = 0; i < size; i++)
            {
                array[i] = int.Parse(line[i]);
            }
            Console.WriteLine(LargerThanNeighbour(array));
        }
    }
}