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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

const (
	none = iota
	inc
	dec
)

func main() {
	var n int
	fmt.Scan(&n)
	a := make([]int, n)
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	for i := range a {
		sc.Scan()
		a[i], _ = strconv.Atoi(sc.Text())
	}
	var ans, i int
	for i+1 < len(a) {
		var j, k int
		for j = i; j+1 < len(a); j++ {
			if a[j] <= a[j+1] {
				continue
			} else {
				break
			}
		}
		for k = i; k+1 < len(a); k++ {
			if a[k] >= a[k+1] {
				continue
			} else {
				break
			}
		}
		i += max(j-i, k-i) + 1
		ans++
	}
	// fmt.Println("d00 - i", i)
	if i < len(a) {
		ans++
	}
	fmt.Println(ans)
}
func max(a, b int) int {
	if a >= b {
		return a
	}
	return b
}