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: Wrong Answer)

#![allow(non_snake_case)]

use std::io::{stdin, Read};
use std::str::FromStr;
fn read_option<T: FromStr>() -> Option<T> {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok()
}
fn read<T: FromStr>() -> T {
    let opt = read_option();
    opt.expect("failed to parse token")
}

fn main() {
    let n: usize = read();
    let vec: Vec<i32> = (0..n).map(|_| read()).collect();
    let diffs: Vec<_> = vec.windows(2).map(|a| a[1] - a[0]).collect();
    let mut before = None;
    let mut ans = 0;
    for v in diffs {
        if v < 0 {
            match before {
                None => before = Some(v),
                Some(a) if a <= 0 => before = Some(a),
                Some(a) if a > 0 => {
                    before = None;
                    ans += 1;
                }
                Some(_) => unreachable!(),
            }
        } else if v > 0 {
            match before {
                None => before = Some(v),
                Some(a) if a > 0 => before = Some(a),
                Some(a) if a <= 0 => {
                    before = None;
                    ans += 1;
                }
                Some(_) => unreachable!(),
            }
        } else if v == 0 {
            match before {
                None => before = Some(v),
                Some(_) => {}
            }
        }
    }
    println!("{}", ans + 1)
}