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#include <iostream>
#include <string>
#include <sstream>
#include <vector>

using namespace std;

int main() {
	int n, counter1 = 0, counter2 = 0;
	int direction = 0;
	int up = 1000000001;
	int down = -1000000001;
	vector<int> arr, arr2;
	string numbers, temp;
	cin >> n;
	cin.ignore();
	getline(cin, numbers);

	istringstream stream(numbers);
	while (getline(stream, temp, ' ')) {
		arr.push_back(stoi(temp));
	}

	arr2 = arr;

	direction = -1;
	for (int i = 0; i < n - 1; i++) {
		int left = arr[i];
		int right = arr[i + 1];

		if (left > right) {
			if (direction == -1) {
				arr[i + 1] = up;
				counter1++;
				direction = 0;
			}
			else {
				direction = -1;
			}
		}
		else if (left < right) {
			if (direction == 1) {
				arr[i + 1] = down;
				counter1++;
				direction = 0;
			}
			else {
				direction = 1;
			}
		}
		else {
			if (direction == -1) {
				arr[i + 1] = up;
				counter1++;
				direction = 0;
			}
			else if (direction == 1) {
				arr[i + 1] = down;
				counter1++;
				direction = 0;
			}
		}
	}

	direction = 1;
	for (int i = 0; i < n - 1; i++) {
		int left = arr2[i];
		int right = arr2[i + 1];

		if (left > right) {
			if (direction == -1) {
				arr2[i + 1] = up;
				counter2++;
				direction = 0;
			}
			else {
				direction = -1;
			}
		}
		else if (left < right) {
			if (direction == 1) {
				arr2[i + 1] = down;
				counter2++;
				direction = 0;
			}
			else {
				direction = 1;
			}
		}
		else {
			if (direction == -1) {
				arr2[i + 1] = up;
				counter2++;
				direction = 0;
			}
			else if (direction == 1) {
				arr2[i + 1] = down;
				counter2++;
				direction = 0;
			}
		}
	}

	if (counter1 > counter2) {
		counter1 = counter2;
	}
	cout << counter1;
}