#include <bits/stdc++.h>
using namespace std;
struct node{int x,y;}a[1100];
bool cmp(node n1,node n2)
{
    if(n1.x!=n2.x) return n1.x<n2.x;else return n1.y<n2.y;
}
int f[1100];
int main() 
{
    int n;scanf("%d", &n);
    for(int i=1;i<=n;i++) scanf("%d%d", &a[i].x, &a[i].y);
    sort(a+1, a+n+1, cmp);
    memset(f, 0, sizeof(f));
    f[n]=1;
    for(int i=n-1;i>=1;i--)
    {
        f[i]=1;
        for(int j=i+1;j<=n;j++)
            if(a[i].y>a[j].y)
                f[i]=max(f[i], f[j]+1);
    }
    int ans=0;for(int i=1;i<=n;i++) ans=max(ans, f[i]);
    printf("%d\n", ans);
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
struct node{int x,y;}a[1100];
bool cmp(node n1,node n2)
{
    if(n1.x!=n2.x) return n1.x<n2.x;else return n1.y<n2.y;
}
int f[1100];
int main() 
{
    int n;scanf("%d",&n);
    for(int i=1;i<=n;i++) scanf("%d%d",&a[i].x,&a[i].y);
    sort(a+1,a+n+1,cmp);
    memset(f,0,sizeof(f));
    f[n]=1;
    for(int i=n-1;i>=1;i--)
    {
        f[i]=1;
        for(int j=i+1;j<=n;j++)
            if(a[i].y>a[j].y)
                f[i]=max(f[i],f[j]+1);
    }
    int ans=0;for(int i=1;i<=n;i++) ans=max(ans,f[i]);
    printf("%d\n",ans);
    return 0;
}