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//Mateusz Kruk
#include <bits/stdc++.h>
using namespace std;
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin>>n;
    vector<int>ciag;
    for(int i=0;i<n;i++){
        int a;
        cin>>a;
        ciag.push_back(a);
    }
    vector<int>ciag2(n,-1); //ciag do pierwszego, ciag2 do drugiego
    for(int i=0;i<n;i++){
        ciag2[i]=ciag[i];
    }
    int e=1; //gdy 1 to w gore, gdy -1 to w dol
    int x=0,y=0;//x do pierszego, y do drugiego
    for(int i=1;i<n;i++){
        if(e==1){
            if(ciag[i-1]<ciag[i]){
                e=-1;
            }
            else{
                x++;
                ciag[i]=INT_MAX-7;
                e=-1;
            }
        }
        else{
            if(ciag[i-1]>ciag[i]){
                e=1;
            }
            else{
                e=1;
                x++;
                ciag[i]=INT_MIN+7;
            }
        }
    }
    e=-1;
    for(int i=1;i<n;i++){
        if(e==1){
            if(ciag2[i-1]<ciag2[i]){
                e=-1;
            }
            else{
                e=-1;
                y++;
                ciag2[i]=INT_MAX-7;
            }
        }
        else{
            if(ciag2[i-1]>ciag2[i]){
                e=1;
            }
            else{
                e=1;
                y++;
                ciag2[i]=INT_MIN+7;
            }
        }
    }
    int ans=min(x,y);
    cout<<ans<<'\n';
}