#include <iostream>
#define MAXN 100050

using namespace std;

int n, a[MAXN], rez;

int main()
{
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
		scanf("%d", &a[i]);
	for (int i = 2; i <= n-1; i++)
		rez += (a[i] > a[i-1] && a[i] > a[i+1]);
	printf("%d\n", rez);
    return 0;
}