1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
#include <iostream>
#include <vector>
#include <array>

int sign(int a, int b)
{
	return b > a ? 1 : (b < a ? -1 : 0);
}

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

	int n;
	std::cin >> n;
	std::vector<int> data(n);
	for (int i = 0; i < n; ++i)
	{
		std::cin >> data[i];
	}

	int total_rising = 0;
	bool rising = true;
	for (int i = 0; i < n - 1; ++i)
	{
		int first = sign(data[i], data[i+1]);
		if (first != 1 && rising || first != -1 && !rising)
		{
			++total_rising;
			++i;
			continue;
		}
		rising = !rising;
	}

	int total_falling = 0;
	bool falling = true;
	for (int i = 0; i < n - 1; ++i)
	{
		int first = sign(data[i], data[i+1]);
		if (first != -1 && falling || first != 1 && !falling)
		{
			++total_falling;
			++i;
			continue;
		}
		falling = !falling;
	}

	//std::cout << total_rising << " " << total_falling << std::endl;
	std::cout << std::min(total_falling, total_rising) << std::endl;
	return 0;
}