下沙的沙子有几粒？

import java.util.*;
 import java.math.*;
 public class Main
 {
     public static void main(String []args)
     {
         Scanner cin=new Scanner(System.in);
         int i,n,m;
         int count=1;
         while(cin.hasNext())
         {    
             m=cin.nextInt();
             n=cin.nextInt();
             BigInteger s1 = BigInteger.valueOf(1);
             BigInteger s2 = BigInteger.valueOf(1);
             BigInteger s3 = BigInteger.valueOf(1);
             for(i=1;i<=n+m;i++)
             {
                 s1=s1.multiply(BigInteger.valueOf(i));
             }
             for(i=1;i<=n;i++)
             {
                  s2=s2.multiply(BigInteger.valueOf(i));
             }
             for(i=1;i<=m;i++)
             {
                  s3=s3.multiply(BigInteger.valueOf(i));
             }
             s2=s2.multiply(s3);
             s1=s1.multiply(BigInteger.valueOf(m+1-n));
             s1=s1.divide(BigInteger.valueOf(m+1));
             System.out.println(s1.divide(s2));    
         }
     }
 }

这个题目和

Buy the Ticket非常相似，具体解释见

Buy the Ticket的解释，只是这里不需要对m 和n进行全排列