#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,i,l=0; 
	cin>>n;
	int j[n];
	for(i=0;i<n;i++){
		cin>>j[i];
	}
	for(i=1;i<n-1;i++){
		if(j[i]>j[i-1]&&j[i]>j[i+1]){
			l++;
		}
	}
	cout<<l;
}
/**************************************************************
	Problem: 1401
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/