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 Python (3.8.2) (judge verdict: Accepted)

import sys
import itertools
# import numpy as np
import time
import math
from heapq import heappop, heappush
from collections import defaultdict
from collections import Counter
from collections import deque
from itertools import permutations
sys.setrecursionlimit(10 ** 7)
 
INF = 10 ** 18
MOD = 10 ** 9 + 7
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

# map(int, input().split())
N = int(input())
A = list(map(int, input().split()))

d = [0] * N
for i in range(1, N):
    d[i] = A[i] - A[i - 1]

l = 0
r1 = 1
r2 = 1
ans = 0
while l < N:
    while r1 < N and d[r1] >= 0:
        r1 += 1
    while r2 < N and d[r2] <= 0:
        r2 += 1
    r = max(r1, r2)
    l = r
    ans += 1
    r1 = l + 1
    r2 = l + 1
print(ans)