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# (Mono 4.6.2.0) (judge verdict: Accepted)

#pragma warning disable

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
// Do not use: System.Numerics; at CodeIQ

public class Test
{
    public static void Main()
    {
        var N = Int32.Parse(Console.ReadLine());
        var a = Console.ReadLine().Split(' ').Select(x => Int32.Parse(x)).ToArray();

        int sectionsCount = 1;
        bool increasing = false;
        bool decreasing = false;

        int lastNum = a[0];  // N >= 1 なのでok

        for (int i = 1; i < a.Length; i++)
        {
            if (a[i] > lastNum)
            {
                if (decreasing)
                {
                    sectionsCount++;
                    increasing = decreasing = false;
                }
                else
                {
                    increasing = true;
                }
            }
            else if (a[i] < lastNum)
            {
                if (increasing)
                {
                    sectionsCount++;
                    increasing = decreasing = false;
                }
                else
                {
                    decreasing = true;
                }
            }
            else
            {
                // do nothing
            }

            lastNum = a[i];
        }

        Console.WriteLine(sectionsCount);
    }
}