#include <iostream>
#include <algorithm>
#include <string>
#include <deque>
using namespace std;

int main() {
    int n;
    cin >> n;
    deque<int> v(n);
    for (auto &i : v) {
        cin >> i;
    }
    int res = n;
    auto f = deque<function<bool(int, int)>>{{greater<int>{}, less<int>{}}};
    for (int b = 0; b < 2; b++) {
        int tmp = 0;
        int cnt = 0;
        for (int i = 1; i < n; i++) {
            if (f[(i+b) % 2](v[i], v[i-1])) {
                tmp += (cnt + 1) / 2;
                cnt = 0;
            } else {
                cnt++;
            }
        }
        tmp += (cnt + 1) / 2;
        res = min(res, tmp);
    }
    cout << res << endl;
}