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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AtCoder_Grand_Contest_013
{
    class A
    {
        static void Main(string[] args)
        {
            //配列の長さを取得
            int n = int.Parse(Console.ReadLine());

            // 配列の中身を取得
            string[] a = Console.ReadLine().Split(' ');

            //配列を作る
            int[] N = new int[n];
            for (int i = 0; i < N.Length; i++)
            {
                N[i] = int.Parse(a[i]);

            }

            bool cntFlg = false;
            int cnt = 0;
            int col = 0;
            for (int j = 1; j < N.Length; j++)
            {
                if (cntFlg && col != N[j] - N[j - 1])
                {
                    cntFlg = false;
                    if(j + 1 == N.Length) { cnt++; }
                    continue;

                }

                col = N[j] - N[j - 1];
                if (-1 <= col && col <= 1)
                {
                    cnt = Cnt(ref cntFlg, cnt);
                }
            }
            Console.WriteLine(cnt);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="cntFlg"></param>
        /// <param name="cnt"></param>
        /// <returns></returns>
        private static int Cnt(ref bool cntFlg, int cnt)
        {
            if (cntFlg)
            {
                return cnt;
            }
            else
            {
                cnt++;
                cntFlg = true;
                return cnt;
            }
        }
    }
}