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

#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;
}