239. Remove K Digits

Given a non-negative integer represented as a string num and an integer k, remove exactly k digits so the resulting number is the smallest possible. Return it as a string without leading zeros (return "0" if the result is empty). Input: '"num", k'.

Input: '"num", k'.

Output: Quoted string — the smallest number.

Examples

Input: "1432219", 3
Output: "1219"
Explanation: Remove 4,3,2 -> 1219.

Input: "10200", 1
Output: "200"
Explanation: Remove 1 -> 0200 -> 200.

Input: "10", 2
Output: "0"
Explanation: Remove all -> 0.

Constraints

• 1<=num.length<=10^5
• 0<=k<=num.length

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