10000以内的N!

import java.io.*;
import java.lang.*;
import java.text.*;
import java.util.*;
import java.math.*;
class Main
{
    public static void main(String[] argc)
    {
        Scanner cin=new Scanner(System.in);
        BigInteger a1,n,i;
        while(cin.hasNextBigInteger())
        {
            a1=cin.nextBigInteger();
            n=BigInteger.valueOf(1);
            for(i=BigInteger.valueOf(1);i.compareTo(a1)<=0;i=i.add(BigInteger.valueOf(1)))
            {
                n=n.multiply(i);
            }
            System.out.println(n);
        }
    }
}

 

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