#include<iostream>

using namespace std;

int a[100001];

int main()

{

int n; cin >> n;

for (int i = 0; i<n; ++i) cin>>a[i];

int count = 0;

for (int i = 1; i < n - 1; ++i) {

 if (a[i] > a[i - 1] && a[i] > a[i - 1]) ++count;

}

cout << count<<endl;

return 0;

}