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#include <iostream>
#include <algorithm>

using namespace std;

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

	int MAX = 1000005;
	int MIN = -1000005;

	int n;
	int previousA, previousB, current;
	bool currentResult{};

	bool isLastChange[2]{};
	int result[2] = {};

	bool changeA = true, changeB = false;

	cin >> n;

	cin >> previousA;

	previousB = previousA;

	for (int i = 0; i < n - 1; ++i)
	{
		cin >> current;

		// A - dół

		if (current > previousA)
		{
			if (changeA) // true - dół
			{
				result[0]++;
				previousA = MIN;
			}
			else
			{
				previousA = current;
			}
		}
		else if (current < previousA)
		{
			if (!changeA)
			{
				result[0]++;
				previousA = MAX;
			}
			else
			{
				previousA = current;
			}
		}
		else
		{
			result[0]++;

			if (changeA)
			{
				previousA = MIN;
			}
			else
			{
				previousA = MAX;
			}
		}


		if (current > previousB)
		{
			if (changeB)
			{
				result[1]++;
				previousB = MIN;
			}
			else
			{
				previousB = current;
			}
		}
		else if (current < previousB)
		{
			if (!changeB)
			{
				result[1]++;
				previousB = MAX;
			}
			else
			{
				previousB = current;
			}
		}
		else
		{
			result[1]++;

			if (changeB)
			{
				previousB = MIN;
			}
			else
			{
				previousB = MAX;
			}
		}


		changeA = !changeA;
		changeB = !changeB;
	}

	cout << min(result[0], result[1]);
}