Problem:
Score : 300 points

Problem Statement

You are given three integers A, B and C. Find the minimum number of operations required to make A, B and C all equal by repeatedly performing the following two kinds of operations in any order:

Choose two among A, B and C, then increase both by 1.

Choose one among A, B and C, then increase it by 2.

It can be proved that we can always make A, B and C all equal by repeatedly performing these operations.

Constraints

0 \leq A,B,C \leq 50

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B C

Output

Print the minimum number of operations required to make A, B and C all equal.

Sample Input 1

2 5 4

Sample Output 1

2

We can make A, B and C all equal by the following operations:

Increase A and C by 1. Now, A, B, C are 3, 5, 5, respectively.

Increase A by 2. Now, A, B, C are 5, 5, 5, respectively.

Sample Input 2

2 6 3

Sample Output 2

5

Sample Input 3

31 41 5

Sample Output 3

23

Solution in Rust (1.15.1) (judge verdict: Accepted)

fn main() {
    let v: Vec<i32> = read_vec();
    let m = v.iter().max().unwrap() * 3 - v.iter().sum::<i32>();
    if m % 2 == 0 {
        println!("{}", m / 2);
    } else {
        println!("{}", (m + 3) / 2);
    }
}

// ========== 以下使い捨て関数  ===============================



// ========== 以下作り置き関数 ================================
pub use std::io::*;
pub use std::process::exit;
pub use std::str::FromStr;

pub const MOD: i64 = 1_000_000_007;

/// 標準入力から
/// 空白文字で囲まれた1つのトークンを
/// 指定の型に変換する
pub fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

/// 標準入力から1行読み取り
/// 空白文字で区切って
/// 指定の型のVecに格納する
pub fn read_vec<T: FromStr>() -> Vec<T> {
    let mut s = String::new();
    stdin().read_line(&mut s).ok();
    s.trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}