#include<bits/stdc++.h>
#define F(i,l,r) for(int i=(l),i##end=(r);i<=i##end;++i)
#define G(i,l,r) for(int i=(l),i##end=(r);i>=i##end;--i)
#define x first
#define y second
#define pii pair<int,int>
#define mp(x,y) make_pair(x,y)
#define ep emplace_back
using namespace std;
typedef long long ll;
int a[5000009];
void read(int &x)
{
	x=0;
	char ch=getchar();
	while(ch<'0'||ch>'9')ch=getchar();
	while(ch>='0'&&ch<='9')x=(x<<3)+(x<<1)+(ch^'0'),ch=getchar();
}
mt19937 rnd(time(0));
int p[100];
int main()
{
	int n;
	read(n);
	F(i,1,n)read(a[i]);
	int T=100;
	int score=22;
	while(T--)
	{
		int x=0;bool flag=true;
		F(i,1,n)
		{
			int mn=100,mx=0;
			F(j,1,x)
			{
				
				mn=min(mn,p[j]);
				if(p[j]<=a[i]&&p[j]>=p[mx])mx=j;
			}
			if(p[mx]==a[i])
			{
				flag=true;
				continue;
			}
			if(!flag)
			{
				if(mx!=0)p[mx]=a[i];
				else p[++x]=a[i];
				flag=true;
				continue;
			}
			if(mx==0&&a[i]<mn&&a[i]>a[i+1])
			{
				flag=false;
				continue;
			}
			if(mx==0&&a[i]>a[i+1])
			{
				flag=false;
				continue;
			}
			if(a[i]>a[i+1]&&a[i+1]>=mn)
			{
				flag=false;
				continue;
			}
			if(mx!=0)p[mx]=a[i];
			else p[++x]=a[i];
			flag=true;
		}
		score=min(score,x);
	}
	cout<<score<<'\n';
	return 0;
}