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.Linq;

namespace AGC013
{
    class A
    {
        static void Main(string[] args)
        {

            int N = int.Parse(Console.ReadLine());
            int[] A = Console.ReadLine().Split().Select(int.Parse).ToArray();

            int count = 1;
            int flag = 0;
            for (int i = 0; i < N - 1; i++)
            {
                if (flag == 1 && A[i] - 1 == A[i + 1]) { count++; flag = 0; continue; }
                if (flag == -1 && A[i] + 1 == A[i + 1]) { count++; flag = 0; continue; }
                if (A[i] + 1 < A[i + 1] || A[i] - 1 > A[i + 1]) { count++; flag = 0; continue; }

                if (A[i] + 1 == A[i + 1]) { flag = 1; }
                if (A[i] - 1 == A[i + 1]) { flag = -1; }

            }
            Console.WriteLine(count);
        }
    }
}