import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Scanner;

public class Main{

    public static void main(String[] args) throws Exception{
        BigInteger n1,n2,n;
        int a,b;
	int resp;
        Scanner input = new Scanner(System.in);
        while(input.hasNext()){
        	a = input.nextInt();
        	b = input.nextInt();
        	n1 = BigInteger.ONE;
        	int c = a-b;
        	for(int i=a; i>c; i--){
        		n1 = n1.multiply(BigInteger.valueOf(i));
        	}
        	while(n1.mod(BigInteger.valueOf(2)).equals(BigInteger.ZERO)){
        		n1 = n1.divide(BigInteger.valueOf(2));
			resp++;
        	}
        	System.out.println(n1);
        	//BigInteger limit = n1.pow(BigDecimal.valueOf(0.5));
        	//for(BigInteger i = BigInteger.valueOf(3); i.c ; i=i.add(val))





        	System.out.println("fat:" + n1);
        }
    }
}