#include <bits/stdc++.h>   using namespace std;   const long long MOD = 1000000007;   const long long MAX = 100005;   const long double PI = 3.14159265359;   const long double G = 9.807;   const long long INF = 1e18;   const long double EPS = 1e-6;   long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }   bool isprime(long long a) {     if (a == 2) return 1;     if (!(a & 1)) return 0;     for (long long i = 3; i * i <= a; i += 2)       if (a % i == 0) return 0;     return 1;   }   long long mpow(long long base, long long exponent, long long modulus) {     if (modulus == 1) return 0;     long long result = 1;     base = base % modulus;     while (exponent) {       if (exponent % 2 == 1) result = (result * base) % modulus;       exponent = exponent >> 1;       base = (base * base) % modulus;     }     return result;   }   long long minv(long long a, long long mod) {     long long _gcd = gcd(a, mod);     assert(_gcd == 1);     return mpow(a, mod - 2, mod);   }   long long n;   long long ans;   long long a[1005];   int main() {     ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);     cin >> n;     for (int i = 1; i <= n; ++i) {       cin >> a[i];     }     for (int i = 2; i < n; ++i) {       if (a[i - 1] > a[i] and a[i] < a[i + 1])         ans++;       else if (a[i - 1] < a[i] and a[i] > a[i + 1])         ans++;     }     cout << ans;     return 0;   }   