Swap Frenzy

Image by
Katey

You are given a positive integer $n$ and asked to make it larger by
swapping pairs of its digits. For each swap, you can choose two
digits at different positions and exchange their positions, as
long as the swap does not result in a leading zero. What is the
largest number you can get after performing **exactly** $k$
swaps?

The input has a single line with two integers $n$ ($100 \leq n < 10^{18}$) and $k$ ($1 \leq k \leq 18$).

Output the largest number you can get after exactly $k$ swaps.

Sample Input 1 | Sample Output 1 |
---|---|

1374 2 |
7413 |

Sample Input 2 | Sample Output 2 |
---|---|

210 1 |
201 |

Sample Input 3 | Sample Output 3 |
---|---|

666 3 |
666 |