PYTHON - How come a number inputted by a user isn't recognized if I try to find it's index?

Question

a = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]

num = input(\'Enter a number: \')
a.append(int(num))
a.sort()
print(a)
print(a.index(num))

Enter a n