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

namespace AGC013SortedArrays
{
    class Program
    {
        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());
            int[] A = new int[N];
            string[] vals = Console.ReadLine().Split(' ');
            for(int i=0; i < N; i++)
            {
                A[i] = int.Parse(vals[i]);
            }
            int num = 1;
            int m = 0;
            if(N == 1)
            {
                Console.WriteLine(1);
                return;
            }
            for(int i=1; i < N; i++)
            {
                if(m == 0)
                {
                    if(A[i] > A[i-1])
                    {
                        m = 1;
                    }
                    else if(A[i] < A[i-1])
                    {
                        m = -1;
                    }
                }
                else if(m == 1)
                {
                    if(A[i] < A[i-1])
                    {
                        num++;
                        m = 0;
                    }
                }
                else if(m == -1)
                {
                    if(A[i] > A[i-1])
                    {
                        num++;
                        m = 0;
                    }
                }
            }
            Console.WriteLine(num);
        }
    }
}