#include<bits/stdc++.h>
using namespace std;

int main(){
    int n, x, counter = 0;
    vector<int>nums;

    cin >> n;

    for(int i = 1; i<= n; i++){
        cin >> x;
        nums.push_back(x);
    }
    for(int i = 1; i < n - 1; i++){
        if((nums[i] >= nums[i+1]) || (nums[i] <= nums[i-1])){
            counter++;
        }
    }
    cout << counter;


    return 0;
}