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

Output

Print the answer.