【codeforces#25B】 Phone numbers

B. Phone numbers

time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

Phone number in Berland is a sequence of n digits. Often, to make it easier to memorize the number, it is divided into groups of two or three digits. For example, the phone number 1198733 is easier to remember as 11-987-33. Your task is to find for a given phone number any of its divisions into groups of two or three digits.
Input

The first line contains integer n (2 ≤ n ≤ 100) — amount of digits in the phone number. The second line contains n digits — the phone number to divide into groups.
Output

Output any of divisions of the given phone number into groups of two or three digits. Separate groups by single character -. If the answer is not unique, output any.
Sample test(s)
Input

6
549871

Output

54-98-71

Input

7
1198733

Output

11-987-33

题意：给一串长度为n的数字串，在两个或三个数字之间加-，便于记忆。

解题思路：可以将数字串都3个3个分，遇到余数不同的分情况讨论。

code：

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