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: Runtime Error)

use std::io::*;
use std::str::FromStr;

//https://qiita.com/tubo28/items/e6076e9040da57368845
fn read<T: FromStr>() -> 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().expect("failed to parse token")
}

fn main() {
    let n:usize = read();
    let x: Vec<u64> = (0..n).map(|_| read()).collect();
    let mut ans = 0;
    let mut d: Vec<u8> = Vec::new();
    let mut skip = false;

    for i in 0..n-1 {
        if x[i] < x[i+1]{ //増加
            d.push(1);
        }else if x[i] > x[i+1]{ //減少
            d.push(2);
        }else{
        }
    }

    let mut status = d[0]; //増加:1 減少：2

    //Down UpやUp Downの切れ目を探す。
    for i in 0..d.len() {
        if skip {
            status = d[i];
            skip = false;
            continue;
        }
        if status != d[i] {
            status = d[i];
            ans += 1;
            skip = true;
        }
    }

    //println!("{:?}", d);
    println!("{}", ans+1);
}