# -*- coding: utf-8 -*-
N = int(raw_input())
A = map(int, raw_input().split())

assert 3 <= N <= 100
assert all([1 <= A[i] <= 100 for i in xrange(N)])
assert len(A) == N


def check(B):
    d = sorted(B)
    if d[0] < d[1] < d[2]:
        if d[1] == B[0] or d[1] == B[2]:
            return True
    return False


print sum(check(A[i:i + 3]) for i in xrange(N - 2))