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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <vector>
#include <algorithm>

#define REP(i,a,b) for(int i=int(a);i<int(b);i++)

using namespace std;

typedef long long int lli;

int main () {
    int N;
    cin >> N;
    vector<int> v(N);
    REP (i, 0, N) cin >> v[i];
    int res = 1 << 30;
    REP (_, 0, 2) {
        bool isUp = false;
        bool isDown = false;
        int ans = 1;
        for (int i = 1; i < N; i++) {
            if (isUp && v[i - 1] > v[i]) {
                ans++;
                isUp = isDown = false;
                continue;
            } else if (isDown && v[i - 1] < v[i]) {
                ans++;
                isUp = isDown = false;
                continue;
            }
            if (v[i] != v[i - 1]) {
                isUp = v[i - 1] < v[i];
                isDown = v[i - 1] > v[i];
            }
        }
        res = min(res, ans);
        reverse(v.begin(), v.end());
    }
    cout << res << endl;
    return 0;
}