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#include <iostream>
#include <limits.h>
using namespace std;

enum : char {
	AMBIGUOUS, INCREASING, DECREASING
} next_step;

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

	int n, answer = 0;
	cin >> n;

	int arr[n];
	for(auto& i : arr)
		cin >> i;

	if(arr[0] == arr[1]) {
		if(arr[1] < arr[2])
			arr[0] = INT32_MAX;
		else if(arr[1] > arr[2])
			arr[0] = INT32_MIN;
	}

	for(int* i = arr+1; i < arr+n; ++i) {
		if(*i == i[-1]) {
			if(next_step == AMBIGUOUS)
				++i;
			next_step = AMBIGUOUS;
			++answer;
		} else if(next_step == INCREASING && i[-1] > *i) {
			++answer;
			*i = INT32_MAX;
		} else if(next_step == DECREASING && i[-1] < *i) {
			++answer;
			*i = INT32_MIN;
		}
		next_step = i[-1] == *i ? AMBIGUOUS : i[-1] < *i ? DECREASING : INCREASING;
	}

	cout << answer;
}