#include <iostream>
#include <algorithm>
using namespace std;
int n, l, r, a[100009];
int main() {
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> l >> r;
		for (int j = r; j <= 100000; j++) {
			if (a[j] == 1) {
				a[j] = 0;
				break;
			}
		}
		for (int j = l; j < r; j++) {
			if (a[j] == 1) a[j + 1] = 1, a[j] = 0;
		}
		a[l] = 1;
	}
	int ret = 0;
	for (int i = 0; i <= 100000; i++) ret += a[i];
	cout << ret << endl;
	return 0;
}