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 (1.42.0) (judge verdict: Accepted)

use std::io::*;
use std::str::FromStr;
use std::cmp;
use std::collections::HashMap;
use std::collections::HashSet;
use std::char;
use std::cmp::min;
use num_traits::abs;

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")
}

fn read_tuple2<T: FromStr, S: FromStr>() -> (T, S) {
    let a = read();
    let b = read();
    (a, b)
}

fn read_tuple3<T: FromStr, S: FromStr, R: FromStr >() -> (T, S, R) {
    let a = read();
    let b = read();
    let c = read();
    (a, b, c)
}

fn count_two(n: u64) -> u64 {
    fn go(count: u64, num: u64) -> u64 {
        if num % 2 == 0 {
            go(count + 1, num / 2)
        } else {
            count
        }
    }
    go(0, n)
}

fn main() {
    let (a, b, c): (u64, u64, u64) = read_tuple3();
    let mut v = vec![a, b, c];
    v.sort();
    let mut count = 0;
    loop {
        if v[0] == v[1] && v[1] == v[2] {
            break;
        }
        if v[2] == v[1] {
            v[0] += 2;
        } else {
            v[0] += 1;
            v[1] += 1;
        }
        v.sort();
        count += 1;
    }
    println!("{}", count);
}