C++ :

#include <iostream>
#include<cstdio>
int fnPartition(int a[], int low, int high)
{
	int i,j;
	int x = a[low];
	i = low; j = high;
	while(i <j)
	{
		while(i <j && x <a[j])
		  j = j-1;
		if(i <j)
		{
			a[i] = a[j];
			i++;
		}
		while(i <j && x>=a[i])
			i++;
		if(i <j)
		{
			a[j] = a[i];
			j--;
		}
	}
	a[i] = x;
	return i;
}
void fnQuickSort(int a[],int low, int high)
{
	int pos;
	if(low < high)
	{
		pos = fnPartition(a,low,high);
		fnQuickSort(a,low,pos-1);
		fnQuickSort(a,pos+1,high);
	}
}//快排
int fnSchedule(int a[],int b[],int s,int e)
{
	int n=0;
	int i=s+1;
	if (a[s]>-1)
	{
		n = 1;
		for(; i <=e; i++)
		if(a[i]>=b[s])
		s++;
		else
		n++;
	}
	return n;
	}
int main(void)
{
	int n,i;
	while(1 == scanf("%d",&n))
	{
		int *st = new int [n];
		int *et = new int [n];
		for (i = 0; i <n; i++)
		scanf("%d %d",&st[i],&et[i]);
		fnQuickSort(st,0,n-1);
		fnQuickSort(et,0,n-1);
        printf("%d\n",fnSchedule(st,et,0,n-1));
		delete []st;
		delete []et;
	}
	return 0;
}