#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <string>
#include <iomanip>
#include <vector>
#include <set>
#include <algorithm>
#define MAXN 0x7fffffff
using namespace std;
int a[1000],b,c,d,s,f[1000][2];
int main(void)
{
	freopen("missilea.in","r",stdin);
	freopen("missilea.out","w",stdout);
	scanf("%d",&b);
	while (b!=0)
	{
		s=1;
		for (c=0;c<b;c++) scanf("%d",&a[c]);
		for (c=0;c<1000;c++) 
		{
			f[c][1]=-MAXN;
			f[c][0]=-MAXN;
		}
		f[0][1]=1;
		for (c=1;c<b;c++)
		{
			for (d=c-1;d>=0;d--)
			{
				if ((f[d][0]!=-MAXN)&&(a[c]>a[d])) f[c][1]=f[c][1]>f[d][0]+1?f[c][1]:f[d][0]+1;
				if ((f[d][1]!=-MAXN)&&(a[c]<a[d])) f[c][0]=f[c][0]>f[d][1]+1?f[c][0]:f[d][1]+1;
			}
			if ((f[c][0]==-MAXN)&&(f[c][1]==-MAXN)) f[c][1]=1;
		}
		for (c=0;c<b;c++)
		{
			s=f[c][0]>s?f[c][0]:s;
			s=f[c][1]>s?f[c][1]:s;
		}
		printf("%d\n",s);
		scanf("%d",&b);
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}