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#include <iostream>
using namespace std;

int n, ai1, ai2, new_ai;

int main()
{
    cin >> n;
    cin >> ai1;
    ai2 = ai1;
    int trend = -1, count1 = 0, count2 = 0, count;

    for (int i = 0; i < n - 1; i++)
    {
        cin >> new_ai;
        if ((new_ai - ai1) * trend <= 0)
        {
            count1++;
            ai1 = trend * 1000001;
        }
        else
            ai1 = new_ai;

        trend = -trend;

        if ((new_ai - ai2) * trend <= 0)
        {
            count2++;
            ai2 = trend * 1000001;
        }
        else
            ai2 = new_ai;
    }

    count = (count1 <= count2) ? count1 : count2;
    cout << count;

    return 0;
}