Geek works at the post office and he writes the following types of letters.
Corporate Letters: 12 letters of this type can be written in an hour.
Informal Letters: 10 letters of this type can be written in an hour.
Given N number of letters, find the minimum number of hours he needs to generate a combination of both types without wasting any time.

Example 1:
Input: N = 33
Output: -1
Explaination: 33 letters can not be generated
without wasting any time.

Example 2:
Input: N = 36
Output: 3
Explaination: 36 corporate letters can
be written in 3 hours.

Your Task:
You do not need to read input or print anything. Your task is to complete the function minHours() which takes the value N as input parameters and returns the minimum hours. Return -1 if N letters cannot be written without wasting any time.

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(1)

Constraints:
1 ≤ N ≤ 10^{5}

见题面

见题面