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

input

output

input

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;

}

巴特西

Testing Round #12 B

最新文章

热门文章