a = list(map(int, input().split())) cnt = 0 for i in range(n-2): if a[i] == a[i+1] or a[i+1] == a[i+2] or a[i] == a[i+2]: continue if a[i] < a[i+1] < a[i+2] or a[i] > a[i+1] > a[i+2]: continue cnt += 1 print(cnt)