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)

using System;
using System.Collections;
using System.Linq;
namespace AGC013A
{
    class Program
    {
        static void ShowAL(ArrayList al)
        {
            for (int i = 0; i < al.Count; i++)
                Console.Write("{0} ", (int)al[i]);
            Console.WriteLine();
        }
        static int Main()
        {
            int n = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
            int ans = 0;
            ArrayList al = new ArrayList();
            for (int i = 0; i < n - 1; i++)
                if (a[i] != a[i + 1])
                    al.Add(a[i]);
            al.Add(a[n - 1]);
            //ShowAL(al);
            a = (int[])al.ToArray(typeof(int));
            al = new ArrayList();
            for (int i = 0; i < a.Length; i++)
            {
                if (al.Count < 2)
                {
                    al.Add(a[i]);
                    continue;
                }
                if ((int)al[al.Count - 2] < (int)al[al.Count - 1] && (int)al[al.Count - 1] > a[i])
                {
                    ans++;
                    //ShowAL(al);
                    al = new ArrayList();
                    al.Add(a[i]);
                    continue;
                }
                if ((int)al[al.Count - 2] > (int)al[al.Count - 1] && (int)al[al.Count - 1] < a[i])
                {
                    ans++;
                    //ShowAL(al);
                    al = new ArrayList();
                    al.Add(a[i]);
                    continue;
                }
                al.Add(a[i]);
            }
            //ShowAL(al);
            ans++;
            Console.WriteLine(ans);
            return 0;
        }
    }
}