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#pragma GCC optimize("Ofast")

#include <iostream>

#include <vector>

#include <climits> //INT_MAX

#define UP   0 
#define DOWN 1

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

	int n; std::cin >> n;

	int* arr = new int[n];
	for(int i = 0; i < n; i++)
	{
		std::cin >> arr[i];
	}

	//4 scenarions
	//1. increasing, first unchanged
	//2. increasing, first decreased
	//3. decreasing, first unchanged
	//4. decreasing, first increased
	//output minimal value out of them

	int answ = INT_MAX;
	
	#pragma GCC unroll 2
	for(int d = UP; d <= DOWN; d++)
	{
		int temp_answ = 0;
		bool next = d;
		bool prev_changed = false;
		for(int i = 1; i < n; i++)
		{
			if(next == UP)
			{
				if(arr[i - 1] >= arr[i] && prev_changed == false)
				{
					temp_answ++;
					prev_changed = true;
				}
				else
					prev_changed = false;
			}
			else if(arr[i - 1] <= arr[i] && prev_changed == false)
			{
				prev_changed = true;
				temp_answ++;
			}
			else
				prev_changed = false;
			

			next = !next;
		}

		if(temp_answ < answ)
			answ = temp_answ;
	
		//now the same but we assume weve changed the first one
		temp_answ = 1;
		next = d;
		prev_changed = true;
		for(int i = 1; i < n; i++)
		{
			if(next == UP)
			{
				if(arr[i - 1] >= arr[i] && prev_changed == false)
				{
					temp_answ++;
					prev_changed = true;
				}
				else
					prev_changed = false;
			}
			else if(arr[i - 1] <= arr[i] && prev_changed == false)
			{
				prev_changed = true;
				temp_answ++;
			}
			else
				prev_changed = false;
			

			next = !next;
		}

		if(temp_answ < answ)
			answ = temp_answ;

	}


	std::cout << answ << '\n';
	delete arr;
}