A - Arithmetic Sequence /

### 問題文

3 項からなる整数列 A = (A_1, A_2, A_3) が与えられます。あなたはこの数列に対して、次の操作を何回でも行うことができます：

• i\in \{1,2,3\} をひとつ選び、A_i1 を加える。

### 制約

• 1\leq A_1, A_2, A_3\leq 10^{15}

### 入力

A_1 A_2 A_3


### 入力例 1

4 8 10


### 出力例 1

2


i = 1i = 3 に対して 1 回ずつ操作を行うと、等差数列 (5, 8, 11) が得られます。

### 入力例 2

10 3 4


### 出力例 2

4


i = 2 に対して 4 回の操作を行うと、等差数列 (10, 7, 4) が得られます。

### 入力例 3

1 2 3


### 出力例 3

0


### 入力例 4

1000000000000000 1 1000000000000000


### 出力例 4

999999999999999


Score : 300 points

### Problem Statement

Given is a sequence of three integers A = (A_1, A_2, A_3). On this sequence, you can do the following operation any number of times:

• choose i\in \{1,2,3\} and add 1 to A_i.

Find the minimum number of operations needed to make A arithmetic. Here, the sequence A = (A_1, A_2, A_3) is arithmetic when A_2 - A_1 = A_3 - A_2 holds.

### Constraints

• 1\leq A_1, A_2, A_3\leq 10^{15}

### Input

Input is given from Standard Input in the following format:

A_1 A_2 A_3


### Sample Input 1

4 8 10


### Sample Output 1

2


One operation with i = 1 and then one operation with i = 3 yield an arithmetic sequence (5, 8, 11).

### Sample Input 2

10 3 4


### Sample Output 2

4


Four operations with i = 2 yield an arithmetic sequence (10, 7, 4).

### Sample Input 3

1 2 3


### Sample Output 3

0


The sequence A is already arithmetic from the beginning, so we need zero operations.

### Sample Input 4

1000000000000000 1 1000000000000000


### Sample Output 4

999999999999999