'''
Created on Mar 16, 2017

@author: Madalina
'''

def factorial(x):
    if x == 0:
        return 1
    result = 1
    for i in range(2, x + 1):
        result = result * i
        
    return result

def combinari(n, k):
    fact1 = factorial(n)
    fact2 = factorial(k)
    fact3 = factorial(n - k)
    return fact1 // (fact2 * fact3)

def compute(stack, n):
    soldiers = n
    total = 1
    for i in range(len(stack)):
        total = total * combinari(soldiers, stack[i])
        soldiers = soldiers - stack[i]
        
    return total

def back(stack, n, m, summ):
    if len(stack) == m and summ == n:
        back.count = back.count + compute(stack, n)
    else:
        for i in range(1, n):
            if summ + i <= n:
                stack.append(i)
                back(stack, n, m, summ + i)
                del stack[-1]

string = input()
string = string.split()
n = int(string[0])
m = int(string[1])
soldiers = []
for i in range(n):
    soldiers.append(str(i))
back.count = 0
back([], n, m, 0)

print((m - 1) * back.count)