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#include<bits/stdc++.h>
using namespace std;

int n, a[50004], ans;
pair <int, int> dp[50004];

void f(int k)
{
	dp[0].second = 1;

	for(int i = 1; i < n; i ++){
		if(i % 2 == k){
			if(a[i - 1] < a[i])
				dp[i].first = min(dp[i - 1].first, dp[i - 1].second);
			else
				dp[i].first = dp[i - 1].second;
		}
		else
		{
			if(a[i] < a[i - 1])
				dp[i].first = min(dp[i - 1].first, dp[i - 1].second);
			else
				dp[i].first = dp[i - 1].second;
		}
		dp[i].second = min(dp[i - 1].first, dp[i - 1].second) + 1;
	}
}


int main()
{
	cin >> n;

	for(int i = 0; i < n; i ++){
		cin >> a[i];
	}
	f(0);
	ans = min(dp[n - 1].first, dp[n - 1].second);
	f(1);
	ans = min(ans,min(dp[n - 1].first, dp[n - 1].second));

	cout<< ans << "\n";


	return 0;
}