Poj Solution 2726

http://poj.org/problem?id=2726

//* @author: 82638882@163.com
import java.io.*;
import java.util.Arrays;
class Main
{
 public static void main(String[] args) throws IOException
 {
  InputStreamReader is=new InputStreamReader(System.in);
  BufferedReader in=new BufferedReader(is);
  while(true)
  {
    int a=Integer.parseInt(in.readLine());
    if(a==0) break;
    my[] p=new my[a];
    for(int i=0;i< a;i++)
    {
    String[] ss=in.readLine().split(" ");
    p[i]=new my(Integer.parseInt(ss[0]),Integer.parseInt(ss[1]));
    }
    Arrays.sort(p);
    int cnt=0;
    for(int i=1,n=0;i< a;i++)
    {
    if(p[n].a==p[i].a){
        cnt++;
        n=i;
    }
    else if(p[n].b<=p[i].b) cnt++;
    else n=i;
     }
     System.out.println(a-cnt);
    }
  }    
}
class my implements Comparable< my>
{
    int a,b;
    public my(int x,int y)
    {
        a=x;
        b=y;
    }
    public int compareTo(my o) {
        if(a==o.a)return o.b-b;
        return a-o.a;
    }
}