#include <bits/stdc++.h>
using namespace std;

struct note{
	long long da=0,dui=0;
}; 
bool cmp(note a,note b){
	return a.da<b.da;
}
int main(){
	int ma=0,n;
	cin>>n;
	note a[n+5];
	int b[n+5],c[n+5];
	memset(b,0,sizeof(b));
	memset(c,0,sizeof(c));
	for(int i=1;i<=n;i++){
		cin>>a[i].da>>b[i];
		a[i].dui=i;
	}
	sort(a+1,a+n+1,cmp);
	for(int i=n;i>=1;i--){
		int mj=0;
		for(int j=i+1;j<=n;j++){	
			if(b[a[i].dui]<b[a[j].dui]){
				if(c[a[j].dui]>mj){
					mj=c[a[j].dui]+1;
				}
				
			}
		}
		if(mj==0){
			c[a[i].dui]=1;
		}else{
			c[a[i].dui]=mj;
		}
		if(c[a[i].dui]>ma){
			ma=c[a[i].dui];
		}
	}
	cout<<ma;
	return 0;
}