#include<fstream>
using namespace std;
int v[5009],n,minim;
int l[5009],poz[5009],incepe[5009];
void minimul();
void solve();
int main()
{
	ifstream fin("subsir2.in");
	ofstream fout("subsir2.out");
	fin>>n;
	int i;
	for(i=1;i<=n;i++)
	   fin>>v[i],l[i]=n,poz[i]=-1;
	solve();
	minimul();
	fout<<minim;
	return 0;
}   
void solve()
{
	int i,j;
	l[n]=1;
	incepe[n]=1;
	for(i=n-1;i>=1;i--)
	{
		for(j=i+1;j<=n;j++)
		   if(v[i]<=v[j] && incepe[j]==0)
		   {   
			   incepe[j]=1;
			   if(l[i]>l[j]+1)
			      l[i]=l[j]+1,poz[i]=j;
			}     
		if(l[i]==n)
		   l[i]=1;
	 }
}
void minimul()
{
	int i;
	minim=n;
	for(i=1;i<=n;i++)
		if(l[i]<minim && incepe[i]!=1)
			minim=l[i];
}