Write a Python program to find the number of notes (Sample of notes: 10, 20, 50, 100, 200 and 500 )

I have used python 3.7 compiler for debugging purpose.

def no_notes(a):
  Q = [500, 200, 100, 50, 20, 10]
  x = 0
  for i in range(6):
    q = Q[i]
    x += int(a / q)
    a = int(a % q)
  if a > 0:
    x = -1
  return x
print(no_notes(500))
print(no_notes(560))

Result:
1

3