//
// factorial functions
//
// n should be >= 0
def factorial(n : Int) : Int = {
  if (n < 1)
    1
  else
    n * factorial(n-1)
}
def factorialL(n : Long) : Long = {
  if (n < 1)
    1
  else
    n * factorialL(n-1)
}
def factorialBig(n : BigInt) : BigInt = {
  if (n < 1)
    1
  else
    n * factorialBig(n-1)
}