Description

Romesh is given an integer $n$ and a string num. He has to create the smallest number possible by removing $n$

digits from num $($the removed digits may or may not be contiguous$).$ The value returned must also be a string.

For example. If Ramesh has num $="1432219"$ and $n=3,$ then we must remove the digits $4,3,$ and $2$ to get the

smallest value i$.$e$."1219".$

It should be noted that if after removing $n$ digits, the num is empty, you must return $"0".$ In addition, all leading

zeros must be removed before returning the string.

Can you help Ramesh find a solution to this problem?

Input Format $-$ The first line in input is $n$ and the second line contains a string.

Output Format $-$ Output is a string with the smallest possible value.

Constraints

The first line inputs an integer $n$ and the second line inputs a string num. The length of num is denoted by len.

$n$len

$11$ en $200,000$

Num may contain leading zeros.

in C$++$