#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main() {
int n,a,de,in,start,ans=0;
de=in=1;
cin>>n;
vector<int>v;
for(int i=0;i<n;i++)
{
cin>>a;
v.push_back(a);
}
start = v[0];
for(int i=1;i<n;i++)
{
// if(de == 3 || in == 3)
// {
// ans++;
// de = 1;
// in = 1;
// if((i+1)<n)
// start = v[i+1];
// else
// break;
// i+=2;
// }
if(start > v[i])
{
de++;
if(in>=3)
ans+=in - 2;
in=1;
start = v[i];
}
else if(start < v[i])
{
in++;
if(de>=3)
ans+=de - 2;
de=1;
start = v[i];
}
else
{
if(in>=3)
ans+=in - 2;
if(de>=3)
ans+=de - 2;
de = 1;
in = 1;
start = v[i];
}
}
if(de >= 3)
ans+=de - 2;
if(in >= 3)
ans+=in -2;
cout<<ans<<endl;
}
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