#include<stdio.h>
#include<math.h>
int main()
{
	int n = 0;
	scanf("%d",& n);
	int arr[1001] = { 0 };
	int count = 0;
	for (int i = 0; i < n; i++)
	{
		scanf("%d", &arr[i]);
	}
	for (int i = 1; i < n-1; i++)
	{
		if (arr[i] < arr[i - 1])
		{
			if (arr[i] < arr[i + 1])
			{
				count++;
			}
			else if (arr[i] == arr[i + 1])
			{
				i++;
				count++;
			}
		}
	}
	printf("%d", count);
	return 0;
}