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.
Input
The first line contains integer number $*n*$ ($1 ≤ *n* ≤ 5·10^{5}$) — number of orders. The following $*n*$ lines contain integer values $*l*_{*i*}$ and $*r*_{*i*}$ each ($1 ≤ *l*_{*i*} ≤ *r*_{*i*} ≤ 10^{9}$).
Output
Print the maximal number of orders that can be accepted.
样例
2
7 11
4 7
1
5
1 2
2 3
3 4
4 5
5 6
3
6
4 8
1 5
4 7
2 5
1 3
6 8
2
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