JAVA大数乘法 HDU1042

import java.math.*;
import java.util.Scanner;


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