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#include <algorithm>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <ranges>
#include <set>
#include <string>
#include <vector>

using namespace std;

const int INF = 1e9 + 1;

int f(deque<int> a, bool is_min) {
    int res = 0;
    a.push_front(is_min ? INF : -INF);
    for (int i = 1; i < a.size(); i++) {
        if (is_min && !(a[i] < a[i - 1])) {
            res++;
            a[i] = -(INF + i);
        } else if (!is_min && !(a[i] > a[i - 1])) {
            res++;
            a[i] = (INF + i);
        }
        is_min = !is_min;
    }
    return res;
}

int solve() {
    int n;
    cin >> n;
    deque<int> a(n);
    a.resize(n);
    for (auto &x : a) cin >> x;
    return min(f(a, true), f(a, false));
}

int main() {
    ios::sync_with_stdio(false);
    cin.exceptions(cin.failbit);
    cin.tie(0);
    cout << solve() << "\n";
}