a = [1, 3, 4, 5, 9, 12] b = [4, 5, 6, 7, 5, 5, 9, 9, 9, 9, 9, 10, 11, 12] q = len(a) for i in range(0, q): temp = a[i] if b.count(temp) == 1: b.remove(temp) elif b.count(temp) > 1: x = b.count(temp) for j in range(1, x + 1): b.remove(temp) print(b)