You are playing a solitaire game with three piles of stones of sizes `a`​​​​​​, `b`,​​​​​​ and `c`​​​​​​ respectively. Each turn you choose two different non-empty piles, take one stone from each, and add `1` point to your score. The game stops when there are fewer than two non-empty piles (meaning there are no more available moves).

Given three integers `a`​​​​​, `b`,​​​​​ and `c`​​​​​, return the maximum score you can get.

Example 1:

    Input: a = 2, b = 4, c = 6
    Output: 6
    Explanation: The starting state is (2, 4, 6). One optimal set of moves is:
    - Take from 1st and 3rd piles, state is now (1, 4, 5)
    - Take from 1st and 3rd piles, state is now (0, 4, 4)
    - Take from 2nd and 3rd piles, state is now (0, 3, 3)
    - Take from 2nd and 3rd piles, state is now (0, 2, 2)
    - Take from 2nd and 3rd piles, state is now (0, 1, 1)
    - Take from 2nd and 3rd piles, state is now (0, 0, 0)
    There are fewer than two non-empty piles, so the game ends. Total: 6 points.

Example 2:

    Input: a = 4, b = 4, c = 6
    Output: 7
    Explanation: The starting state is (4, 4, 6). One optimal set of moves is:
    - Take from 1st and 2nd piles, state is now (3, 3, 6)
    - Take from 1st and 3rd piles, state is now (2, 3, 5)
    - Take from 1st and 3rd piles, state is now (1, 3, 4)
    - Take from 1st and 3rd piles, state is now (0, 3, 3)
    - Take from 2nd and 3rd piles, state is now (0, 2, 2)
    - Take from 2nd and 3rd piles, state is now (0, 1, 1)
    - Take from 2nd and 3rd piles, state is now (0, 0, 0)
    There are fewer than two non-empty piles, so the game ends. Total: 7 points.

Example 3:

    Input: a = 1, b = 8, c = 8
    Output: 8
    Explanation: One optimal set of moves is to take from the 2nd and 3rd piles for 8 turns until they are empty.
    After that, there are fewer than two non-empty piles, so the game ends.

Constraints:

- `1 <= a, b, c <= 105`