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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
int main() {
	int N;
	scanf("%d", &N);
	int *A = (int *)malloc(sizeof(int)*N);
	for (int i = 0; i < N-1; i++)
	{
		scanf("%d", &A[i]);
	}

	int uod = 0;
	int tmp = 0;
	int ans = 0;
	for (int i = 0; i < N-1; i++)
	{
		if (A[i+1] == A[i])
		{
			i++;
		}
		else if (A[i+1] > A[i])//大きい
		{
			if (uod == -1)//減少中の場合は減少終了
			{
				tmp++;//分割
				uod = 0;
			}
			else //その他の場合は増加開始
			{
				uod = 1;
			}
		}

		else if (A[i+1] < A[i])//小さい
		{
			if (uod == 1)//増加中の場合は増加終了
			{
				tmp++;//分割
				uod = 0;
			}
			else //その他の場合は減少開始
			{
				uod = -1;
			}
		}

	}
	ans = tmp + 1;
	printf("%d\n", ans);

	return 0;
}