#include<iostream>
#include<algorithm>
using namespace std;

struct anb
{
	int south;
	int north;
};

anb a[1000010];
int n, i, len, temp;
long d[200005];

bool cmp(anb x, anb y)
{
	return x.north < y.south;
}

int main()
{
	cin >> n;
	for(i = 1; i <= n; i ++ )
		cin >> a[i].north >> a[i].south;
	sort(a + 1, a + 1 + n, cmp);
	
	d[++len]=a[1].south;
	
	for(i = 2; i <= n; i ++ )
	{
		int q = upper_bound(d + 1, d + 1 + len, a[i].south) - d;
		d[q] = a[i].south;
		if (q > len) len ++ ;
	}
	cout << len - 1 << endl;
	return 0;
}