#include <iostream>
#include <algorithm>
using namespace std;
const int inf = 1012345678;
int n, l, r, d[100009];
int main() {
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	for (int i = 0; i <= 100000; i++) d[i] = inf;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> l >> r;
		int pl = lower_bound(d, d + 100001, l) - d;
		int pr = lower_bound(d, d + 100001, r) - d;
		for (int j = pr; j >= pl + 1; j--) d[j] = d[j - 1] + 1;
		d[pl] = l;
	}
	cout << lower_bound(d, d + 100001, inf) - d << endl;
	return 0;
}