Problem Statement

You are given a string $S$ consisting of digits between 1 and 9, inclusive. You will insert at most $K$ commas (,) into this string to separate it into multiple numbers.

Your task is to minimize the maximum number among those produced by inserting commas. Find minimum possible such value.

Constraints

• $0 ≦ K < |S| ≦ 100,000$
• $S$ consists of digits between 1 and 9, inclusive.

Partial Scores

• In the test set worth $100$ points, $|S| ≦ 2$.
• In the test set worth another $100$ points, $|S| ≦ 16$.
• In the test set worth another $200$ points, $|S| ≦ 100$.
• In the test set worth another $200$ points, $|S| ≦ 2,000$.

Input

The input is given from Standard Input in the following format:

$K$ $S$

Output

Print the minimum possible value.

Sample Input 1

2
15267315

Sample Output 1

315

When the string is separated into $152$, $67$ and $315$, the maximum among these is $315$, which is the minimum possible value.

Sample Input 2

0
12456174517653111

Sample Output 2

12456174517653111

$12456174517653111$ itself is the answer.

Sample Input 3

8
127356176351764127645176543176531763517635176531278461856198765816581726586715987216581

Sample Output 3

5317635176