i = int(input("input"))
sum = 0
if i<1:
  exit()
else:
  while i>0:
    b = 2
    c = 1
    while b<=i:
      c=b*c
      b=b+1
    sum += c
    i = i-1
    # print(c)
print(sum)

def fn(x):
  if x==1:
    return 1
  def f(x):
    if x==1:
      return 1
    return f(x-1)*x
  return fn(x-1)+f(x)
n = int(input("请输入值"))
print(fn(n))