import java.math.BigInteger;
import java.util.*;
public class Example{
	

	public staic BigIntegerFactorial(int a){
		BigInteger f = new BigInteger("1");
		 for ( int i=2;i<=a;i++){
			BigInteger x=BigInteger.valueOf(i);
			f =f.multiply(x);
		 }
	
	return f;
		}
	public static void main(String[] args){
		Scanner sc= new Scanner(System.in);
		int a = sc.nextInt();
	  System.out.println(factorial(a));
	 }
}