1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
#include <bits/stdc++.h>
using namespace std;

#define int int64_t
#define pb push_back
#define st first
#define nd second
#define pii pair<int, int>
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()

int tab[50009];
int dp[50009][2][2];

int32_t main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	int n;
	cin >> n;
	for(int i=0;i<n;i++) cin >> tab[i];
	dp[0][0][1] = dp[0][1][1] = 1;
	for(int i=1;i<n;i++) {
		dp[i][0][0] = dp[i][0][1] = dp[i][1][0] = dp[i][1][1] = 1e9;
		if(tab[i]>tab[i-1]) dp[i][1][0] = dp[i-1][0][0];
		dp[i][1][0] = min(dp[i][1][0], dp[i-1][0][1]);
		if(tab[i]<tab[i-1]) dp[i][0][0] = dp[i-1][1][0];
		dp[i][0][0] = min(dp[i][0][0], dp[i-1][1][1]);
		dp[i][1][1] = min({dp[i][1][1], dp[i-1][0][0]+1, dp[i-1][0][1]+1});
		dp[i][0][1] = min({dp[i][0][1], dp[i-1][1][0]+1, dp[i-1][1][1]+1});
	}
	cout << min({dp[n-1][0][0], dp[n-1][0][1], dp[n-1][1][0], dp[n-1][1][1]}) << "\n";
}