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#include <bits/stdc++.h>
#include <random>
#define ll long long int
#define pb push_back
#define st first
#define nd second
#define pii pair<int,int>
#define mp make_pair
#define pll pair<long long,long long>
#define ld long double
#define ull unsigned long long
#define mt make_tuple
    
using namespace std;
    
const int nax = 1e6 + 5;
int a[nax];
int n;
const int inf = 1e9;

int calc(int par){
    // mdmdm
    int ans = 0;
    int last = a[1];
    for(int i=2;i<=n;i++){
        if((i + par) % 2 == 0){
            // wieksze
            if(a[i] <= last){
                ans++;
                last = inf;
            }
            else last = a[i];
        }
        else{
            if(a[i] >= last){
                ans++;
                last = -inf;
            }
            else last = a[i];
        }
    }
    return ans;
}

void solve(){
    cin >> n;
    for(int i=1;i<=n;i++) cin >> a[i];
    int ans = min(calc(0), calc(1));
    cout << ans << "\n";
}
    
int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    
    int tt = 1;
    // cin >> tt;
    while(tt--) solve();
    
    return 0;
}


/*
g++ -std=c++17 -Wall -Wshadow -Wextra -O2 -fsanitize=address -fsanitize=undefined c.cpp -o c
*/