A restaurant received n orders for the rental. Each rental order reserve the restaurant for a continuous period of time, the i -th order is characterized by two time values — the start time l i and the finish time r i ( l i ≤ r i ). Restaurant management can accept and reject orders. What is the maximal number of orders the restaurant can accept? No two accepted orders can intersect, i.e. they can't share even a moment of time. If one order ends in the moment other starts, they can't be accepted both.

输入描述:

The first line contains integer number n (1 ≤ n ≤ 5·105) — number of orders. The following n lines contain integer values li and ri each (1 ≤ li ≤ ri ≤ 109).

输出描述:

Print the maximal number of orders that can be accepted.