#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#define Q 1000010 
using namespace std;
int n,a[Q],b[Q],ANS=0;
int main()
{
	freopen("lunch.in","r",stdin);
	freopen("lunch.out","w",stdout);
	ios::sync_with_stdio(false);
	cin>>n;
	for(int i=1;i<=n;i++)
	 {
             cin>>a[i];
                              }
	for(int i=1;i<=n;i++)
	{
		if(a[i]==0)
			continue;
		int l=1,r=ANS,m;
		while(l<=r)
		{
			m=(l+r)>>1;
			if(b[m]>a[i])l=m+1;
			else r=m-1;
		}
		ANS=max(ANS,l);b[l]=a[i];
	}
 	          cout<<ANS<<endl;
	return 0;
}