Given a positive integer $n$ with $d$ digits, find the largest number possible by removing exactly $k$ digits from the given number.
### Input
- The first line contains a positive integer $n$.
- The second line contains an integer $k$.
### Output
- Print the largest possible integer after removing exactly $k$ digits from the number $n$. This number should not have a leading digit of $0$.
### Constraints
- $1 \le d \le 10^5$.
- $1 \le k < d$.
### Example
Input:
```
4231
2
```
Output:
```
43
```