Remove K Digits

num is a non-negative number written as a string of digits. Remove exactly k digits so that the number left is as small as possible. Return it as a string without leading zeros (return "0" if nothing is left or only zeros are).

For num = "1432219" and k = 3 the answer is "1219".

Examples

Example 1

Input:

remove_k_digits('1432219', 3)

Output:

'1219'

Example 2

Input:

remove_k_digits('10200', 1)

Output:

'200'

Constraints

• 0 <= len(num) <= 200000
• 0 <= k <= len(num)
• num has no leading zeros except the number 0 itself.