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#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n;
    cin >> n;

    vector<int> sounds(n);

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

    vector<int> diffs(n);

    for (int i = 0; i < n - 1; i++) {
        diffs[i] = sounds[i + 1] - sounds[i];   
    }

    int plus_loop_result = 0, minus_loop_result = 0;

    for (int i = 0; i < n - 1; i++) {
        if ((i % 2 == 0 && diffs[i] >= 0) || (i % 2 == 1 && diffs[i] <= 0)) {
            minus_loop_result++;
            i++;
        }
    }

    for (int i = 0; i < n - 1; i++) {
        if ((i % 2 == 1 && diffs[i] >= 0) || (i % 2 == 0 && diffs[i] <= 0)) {
            plus_loop_result++;
            i++;
        }
    }

    cout << min(minus_loop_result, plus_loop_result);
}