Largest Odd Number in a String

num is a string of digits. Return the largest odd number that appears as a substring (a run of consecutive digits) of num, as a string. If there is no odd number in it, return "".

Examples

Example 1

Input:

largest_odd_number('52')

Output:

'5'

5 is the biggest odd substring.

Example 2

Input:

largest_odd_number('4206')

Output:

''

There is no odd digit.

Constraints

• 0 <= len(num) <= 3 * 10**5
• num contains digits and may start with 0.