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Restaurant

4000ms 262144K

Description:

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 li and the finish time ri (li ≤ ri).

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

Output:

Print the maximal number of orders that can be accepted.

Sample Input:

2
7 11
4 7

Sample Output:

1

Sample Input:

5
1 2
2 3
3 4
4 5
5 6

Sample Output:

3

Sample Input:

6
4 8
1 5
4 7
2 5
1 3
6 8

Sample Output:

2

Informação

Codeforces

Provedor Codeforces

Código CF597B

Tags

dpgreedysortings

Submetido 0

BOUA! 0

Taxa de BOUA's 0%

Datas 09/05/2023 09:01:47

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