#include <bits/stdc++.h>   using namespace std;   long long func(long long arr[], long long n) {     long long ans = 0;     for (long long i = 2; i < n; i++) {       if (arr[i] > arr[i - 1] && arr[i] > arr[i + 1]) {         ans++;       } else if (arr[i] < arr[i - 1] && arr[i] < arr[i + 1]) {         ans++;       }     }     return ans;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     long long n;     cin >> n;     long long arr[n + 1];     for (long long i = 1; i <= n; i++) {       cin >> arr[i];     }     cout << func(arr, n) << endl;   }   