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#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    // Read input

    int n;

    cin >> n;

    vector<int> data(n, 0);

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

    // Analyze

    int expected_sign_1 = -1;
    int expected_sign_2 = 1;
    int count_scenario_1 = 0;
    int count_scenario_2 = 0;

    for (int i = 0; i < n - 1; i++) {
        if ((data[i] - data[i + 1]) * expected_sign_1 != 1) {
            count_scenario_1++;
            expected_sign_1  *= -1;
        }
        if ((data[i] - data[i + 1]) * expected_sign_2 != 1) {
            count_scenario_2++;
            expected_sign_2  *= -1;
        }
    }

    cout << max(count_scenario_1, count_scenario_2);

    return 1;
}