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#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned int ui;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<long long> vll;
const ll LINF = 1e18;
const int INF = 1e9;

int signum(int a) {
    return (a > 0) - (a < 0);
}

int count_result(vi &a, int first, int second) {
    vi res(a.size());
    res[0] = 0;
    res[1] = signum(a[1] - a[0]) == first ? 0 : 1;

    swap(first, second);
    for (size_t i = 2; i < res.size(); ++i) {
        if (signum(a[i] - a[i - 1]) == first) {
            res[i] = res[i - 1];
        } else {
            res[i] = res[i - 2] + 1;
        }

        swap(first, second);
    }

    // for (size_t i = 0; i < res.size(); ++i) {
    //     cerr << res[i] << ' ';
    // }
    // cerr << '\n';

    return res.back();
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    vi a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }

    // cerr << count_result(a, 1, -1) << '\n';
    // cerr << count_result(a, -1, 1) << '\n';
    cout << min(count_result(a, 1, -1), count_result(a, -1, 1)) << endl;

    return 0;
}