Problem:
Score : 300 points

Problem Statement

You are given an array A of length N.
Your task is to divide it into several contiguous subarrays.
Here, all subarrays obtained must be sorted in either non-decreasing or non-increasing order.
At least how many subarrays do you need to divide A into?

Constraints

1 \leq N \leq 10^5

1 \leq A_i \leq 10^9

Each A_i is an integer.

Input

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Print the minimum possible number of subarrays after division of A.

Sample Input 1

6
1 2 3 2 2 1

Sample Output 1

2

One optimal solution is to divide the array into [1,2,3] and [2,2,1].

Sample Input 2

9
1 2 1 2 1 2 1 2 1

Sample Output 2

5

Sample Input 3

7
1 2 3 2 1 999999999 1000000000

Sample Output 3

3

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

int main() {
	int n, ans = 1;
	long long a;
	cin >> n;
	vector<long long>hiku;
	vector<long long>suu;
	for (int i = 0; i < n; ++i) {
		long long tmp;
		cin >> tmp;
		suu.push_back(tmp);
	}
	for (int i = 0; i < n - 1; ++i) {
		a = suu[i + 1] - suu[i];
		hiku.push_back(a);
	}
	for (int i = 1; i < n - 2; ++i) {
		if (hiku[i] == 0) {
			hiku[i] = hiku[i - 1];
		}
	}
	for (int i = 0; i < n - 2; ++i) {
		if (hiku[i] * hiku[i + 1] < 0) {
			++ans;
			++i;
		}
	}
	cout << ans << endl;
}