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#include <bits/stdc++.h>

using namespace std;

int n;
int wej[50003];

int calc(bool what)
{
    int res = 0;
    int last = wej[0];
    for (int i = 1; i < n; i++)
    {
        if (what && wej[i] <= last)
        {
            res++;
            last = 10000000;
        }
        else if (!what && wej[i] >= last)
        {
            res++;
            last = -10000000;
        }
        else
            last = wej[i];

        what = !what;
    }
    return res;
}

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

    cin >> n;
    for (int i = 0; i < n; i++)
        cin >> wej[i];

    cout << min(calc(0), calc(1)) << "\n";

    return 0;
}