http://acm.hdu.edu.cn/showproblem.php?pid=2674 （很神奇）

/* * 一开始 2009 后面的全部为0 前面的用BigInteger 暴力 TLE * 后来试了很多收据从41开始后面的数据全部为0 前面的乘下就OK了 */import java.util.*;import java.io.*;import java.math.*;public class Main2674 {//static StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));//static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));static Scanner cin = new Scanner(new BufferedInputStream(System.in));public static void main(String[] args){while(cin.hasNext()){BigInteger a = cin.nextBigInteger();if(a.compareTo(BigInteger.valueOf(41)) >= 0){//out.println(0);System.out.println("0");;continue;}BigInteger ans = BigInteger.ONE;for(int i = 2; i <= a.intValue(); i++){ans = ans.multiply(BigInteger.valueOf(i));}/*long ans = 1;for(int i = 2; i <= a.intValue(); i++){ans = (ans * i) % 2009;}*///System.out.println(ans);//out.println(ans.remainder(BigInteger.valueOf(2009)));System.out.println(ans.remainder(BigInteger.valueOf(2009)));}//out.flush();} }