#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;
}
