1089 Musical Loop uri

//thanks God For Every Thing!
//contest link:
#include<bits/stdc++.h>
#define pi                      acose(-1)

typedef long long int           ll;
typedef double                  dl;
using namespace std;
const int mx = 1e4+5;


int main()
{
    int n, i;
    int arr[10005];

    while(cin>>n && n!=0)
    {
        for(i=0; i<n; i++)
        {
            cin>>arr[i];
        }
        int cnt=0;
        for(i=0; i<n; i++)
        {
            if(arr[i]>arr[i+1])
            {
                if(arr[i+1]<arr[i+2])
                {
                    cnt++;
                }
            }
            if(arr[i]<arr[i+1])
            {
                if(arr[i+1]>arr[i+2])
                {
                    cnt++;
                }
            }

        }
        cout<<cnt<<endl;
    }

    return 0;
}