Roll Dice

Given N dices each face ranging from 1 to 6, return the minimum number of rotations necessary for each dice show the same face.
Notice in one rotation you can rotate the dice to the adjacent face. For example you can rotate the dice shows 1 to show 2, 3, 4, or 5. But to make it show 6, you need two rotations.

Example:
Input: [6, 5, 4]
Output: 2
Rotate 6 to 4, then rotate 5 to 4.

Input: [6, 6, 1]
Output: 2
Rotate 1 to 6, which needs two rotations.

Input: [6, 1, 5, 4]
Output: 3
Rotate 6 to 5, rotate 1 to 5, then rotate 4 to 5




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