Problem

There is a string $ S $ of length $ N $. All characters in $ S $ are numbers between 0 and 9.
When you make a sequence of $\ frac {N \ times (N + 1)} {2}$, which is the number of terms created by enumerating all the numbers created from all the substrings of $ S $, Find the smallest value in $ H $.

Constraints

The input satisfies the following conditions.

• $1 \ leq N \ leq 10 ^ 5$
• $1 \ leq H \ leq \ frac {N \ times (N + 1)} {2}$
• $ | S | = N $
• All characters in $ S $ are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

Input

The input is given in the following format.

$ N $ $ H $
$ S $

All inputs are given as integers.
$ N $ and $ H $ are given on the first line, separated by blanks.
The second line is given the string $ S $ of length $ N $.

Output

Output the $ H $ th value on one line.
(Do not include extra 0s at the beginning of the output.)

Examples

Input

2 3
00

Output

0

Input

4 9
0012

Output

12

Input

5 13
10031

Output

100

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