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#include <iostream>
#include <string>

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

	enum Change
	{
		Raise, Fall, None
	};

	const int min = -1000000;
	const int max = 1000000;

	int changes = 0;

	int n;
	std::cin >> n;

	int prev, current, next;

	Change lastChange = None;

	auto print = [&]()
	{
		std::cout << "[" << prev << " " << current << "]\n";
	};
	
	std::cin >> prev >> current >> next;
	if ((prev < current && current > next) || (prev > current) && (current < next))
	{
		lastChange = current < next ? Raise : Fall;
	}
	else if ((prev == current) && (current == next))
	{
		changes++;
		lastChange = current < next ? Raise : Fall;
	}
	else if (prev == current)
	{
		changes++;
		lastChange = current < next ? Raise : Fall;
	}
	else if (current == next)
	{
		changes++;
		lastChange = current < next ? Raise : Fall;
		if (lastChange == Raise)
		{
			next = min;
			lastChange = Fall;
		}
		else
		{
			next = max;
			lastChange = Raise;
		}
	}
	else
	{
		if (prev < current)
		{
			next = min;
			changes++;
			lastChange = Fall;
		}
		else
		{
			changes++;
			next = max;
			lastChange = Raise;
		}
	}

	prev = next;

	for (int i = 3; i < n; i++)
	{
		std::cin >> current;

		if (lastChange == Raise)
		{
			if (prev <= current)
			{
				current = min;
				changes++;
			}
			lastChange = Fall;
		}
		else
		{
			if (prev >= current)
			{
				current = max;
				changes++;
			}
			lastChange = Raise;
		}

		prev = current;
	}

	std::cout << changes;

	return 0;
}