Sort Digits in String

Given a string that contains both letters and digits, your task is to create a new string in which all the digits are sorted in ascending order, while all the letters remain in their original positions.

For example, if the input string is a3b2c1e, then after sorting only the digits, the resulting string should be a1b2c3e. The positions of the letters (a, b, c, e) do not change.

Note: The input string will consist of alphanumeric characters only.

The sorting for the digits follows the natural order: $$0 < 1 < 2 < \dots < 9$$.

inputFormat

The input is a single line containing a non-empty string composed of letters and digits. The input is provided via standard input (stdin).

outputFormat

The output is a single line: the modified string where the digits are sorted in ascending order while the letters remain in their original positions. The result should be printed to standard output (stdout).

## sample

a3b2c1e

a1b2c3e

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