def N(x,y):
    z = 1
    u = 1
    v = x-y

    for i in range(x):
        p = i + 1
        z = z * p

    for i in range(v):
        p = i + 1
        u = u * p

    final = z / u
    return final


x = int(input("How many Chars ? : "))
y = int(input("How many element ? : "))
print(int(N(x,y)))