#include <cstdlib>
#include <cstdio>
#include <map>
#include <algorithm>
using namespace std;
const int MAXN=100011;
int F[MAXN]={0},A[MAXN],S[MAXN],N;
int L,R,Mid,now;

inline int max(int a,int b)
{
	return a>b?a:b;
}

inline int find(int k)
{
	L=1,R=now,Mid=(L+R)/2;
	while(L<=R)
	{
		if(S[Mid]>k) L=Mid+1;
		else R=Mid-1;
		Mid=(L+R)/2;
	} return Mid;
}

int main()
{ 
	freopen("lunch.in","r",stdin);
	freopen("lunch.out","w",stdout);
	scanf("%d\n",&N);
	for(int i=1;i<=N;i++) scanf("%d",&A[i]),S[i]=0; 
	if(A[1]!=0) {S[1]=A[1]; F[1]=1; now=1;}
	int tmp;
	for(int i=2;i<=N;i++)
	{
		if(A[i]==0) continue;
		tmp=find(A[i])+1;
		if(tmp>F[i]) F[i]=tmp;
		if(tmp>now) now=tmp;
		if(S[F[i]]<A[i]) S[F[i]]=A[i];
	}
	printf("%d\n",*max_element(F+1,F+1+N));
	return 0;
}