【大数问题】大数阶乘

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