Why is the reference count of b = 100

Question

a = 42 # Create object <42>
b = a # Increase ref. count of <42>
c = [a] # Increase ref. count of <42>

del a # Decrease ref. count of <42>
b = 100 # Decrease ref. count of <42>
c[0] = -1 # Decrease ref. count of <42>
decreased. i expect it to increase cos it has been assigned another value.
in the last second line

Answer 1

Python?