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 Rust (1.15.1) (judge verdict: Accepted)

use std::io::Read;

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_to_string(&mut buf).unwrap();

    let answer = solve(&buf);

    println!("{}", answer);
}

fn solve(input: &str) -> String {
    let mut iterator = input.split_whitespace();

    let n: usize = iterator.next().unwrap().parse().unwrap();

    let mut ans: usize = 1;
    let mut increasing: bool = false;
    let mut decreasing: bool = false;

    let mut prev: usize = 0;
    for _ in 0..n {
        let a: usize = iterator.next().unwrap().parse().unwrap();

        // println!("prev = {}, a = {}, inc = {}, dec = {}", prev, a, increasing, decreasing);

        if prev == 0 {
            // do nothing
        } else if !increasing && !decreasing {
            if a < prev {
                decreasing = true;
            } else if a > prev {
                increasing = true;
            }
        } else if increasing && a < prev {
            ans += 1;
            increasing = false;
        } else if decreasing && a > prev {
            ans += 1;
            decreasing = false;
        }

        prev = a;

        // println!("ans = {}", ans);
    }

    return ans.to_string();
}