### ** numericalstrings**

## Problem Description

Peanut has *N* numerical strings, each of them containing only digits '1' to '9' and at most 5 characters long. He wishes to select *K* of these strings, and join them together in a certain order, to form the largest possible resultant number. What is the largest number he can form?

## Input

The first line of input will contain two integers, *N* and *K*.

The next *N* lines of input will contain a single numerical string each.

## Output

The output should contain exactly one number, the largest possible numerical string formed by concatenating *K* of these numerical strings together.

## Limits

For all subtasks: 1 ≤ K ≤ N ≤ 100 000.

Subtask 1 (12%): All numerical strings are 1 character long.

Subtask 2 (17%): All numerical strings are of the same length.

Subtask 3 (11%): K = 1.

Subtask 4 (22%): K = N.

Subtask 5 (38%): No additional constraints.

## Sample Input

5 3
5
541
33
9
98

## Sample Output

9854133