Testing Round #12 B

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.

Examples

input

2
7 11
4 7

output

1

input

5
1 2
2 3
3 4
4 5
5 6

output

3

input

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

output

2
贪心，求最多的不相交线段

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

#include<bits/stdc++.h> using namespace std; struct P {     int s,e; }He[5*100000]; bool cmd(P x,P y) {     return x.e<y.e; } int main() {     int n;     cin>>n;     for(int i=0;i<n;i++)     {         cin>>He[i].s>>He[i].e;     }     sort(He,He+n,cmd);     int sum=He[0].e;     int pos=1;     for(int i=0;i<n;i++)     {         if(He[i].s>sum)         {             sum=He[i].e;             pos++;         }     }     cout<<pos<<endl;     return 0; }