Problem:
Score : 300 points

Problem Statement

Takahashi, Aoki and Snuke love cookies. They have A, B and C cookies, respectively. Now, they will exchange those cookies by repeating the action below:

Each person simultaneously divides his cookies in half and gives one half to each of the other two persons.

This action will be repeated until there is a person with odd number of cookies in hand.

How many times will they repeat this action?
Note that the answer may not be finite.

Constraints

1 ≤ A,B,C ≤ 10^9

Input

Input is given from Standard Input in the following format:

A B C

Output

Print the number of times the action will be performed by the three people, if this number is finite.
If it is infinite, print -1 instead.

Sample Input 1

4 12 20

Sample Output 1

3

Initially, Takahashi, Aoki and Snuke have 4, 12 and 20 cookies. Then,

After the first action, they have 16, 12 and 8.

After the second action, they have 10, 12 and 14.

After the third action, they have 13, 12 and 11.

Now, Takahashi and Snuke have odd number of cookies, and therefore the answer is 3.

Sample Input 2

14 14 14

Sample Output 2

-1

Sample Input 3

454 414 444

Sample Output 3

1

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using static Atcoder;
using System.Threading.Tasks;
using System.ComponentModel;

public class Hello
{
    private const int INF = 1000000007;
    public static void Main()
    {
        long[] ABC = LongLine();
        long A = ABC[0], B = ABC[1], C = ABC[2];
        long ans = -1;
        if (ABC.Count(c => c == A) == 3) ;
        else if (ABC.Any(v => v % 2 == 1)) ;
        else {
            ans = 0;
            long A_, B_, C_;
            while (true) {
                ans++;
                A_ = A / 2;
                B_ = B / 2;
                C_ = C / 2;
                A = B_ + C_;
                B = A_ + C_;
                C = A_ + B_;
                if (A % 2 == 1 || B % 2 == 1 || C % 2 == 1) break;
            }
        }
        Console.WriteLine(ans);
    }
}

public class Factorization
{
    private static long N;

    public Factorization(long n) { N = n; }

    //最大公約数を返す
    public static long GCD(long a, long b)
    {
        if (a < b) return GCD(b, a);
        long r;
        while (b != 0)
        {
            r = a % b;
            a = b;
            b = r;
        }
        return a;
    }

    //素数判定
    public static bool IsPrime(long n)
    {
        if (n < 2) return false;
        if (n == 2) return true;
        if (n % 2 == 0) return false;

        double root = Math.Sqrt(n);
        for (int i = 3; i <= root; i += 2)
        {
            if (n % i == 0) return false;
        }
        return true;
    }

    //試し割り
    private static int[] TryPrimes = new int[] { 2, 3, 5, 7, 11 };
    public long TryAllocation(long p)
    {
        long count = 0;
        while (N % p == 0)
        {
            count++;
            N /= p;
        }
        return count;
    }

    private int[] xi = new int[] { 13, 17, 19, 23, 29 };
    private long f(long x, int suffix)
    {
        return (xi[suffix % xi.Count()] * x + suffix) % N;
    }

    //nを分解
    public long PollardsRho(long n, int suffix = 0)
    {
        //素数を渡すと失敗するらしい
        if (IsPrime(n)) return n; //もう素数
        long x = 2, y = 2, d = 1;
        while (d == 1)
        {
            x = f(x, suffix);
            y = f(f(y, suffix), suffix);
            d = GCD(Math.Abs(x - y), n);
        }
        if (d == n)
        {
            //f(x)を変えて試す
            return PollardsRho(n, suffix + 1);
        }
        return d;
    }

    public IEnumerable<long> Calc()
    {
        //小さな素因数の計算
        foreach (var prime in TryPrimes)
        {
            var box = TryAllocation(prime);
            for (int i = 0; i < box; i++) yield return prime;
        }

        //残りをRhoで解く
        while (true)
        {
            if (N == 1) break;
            var ret = PollardsRho(N);
            yield return ret;
            N /= ret;
        }
    }
}


public class Atcoder
{
    static void Swap<T>(ref T a, ref T b)
    {
        var t = a;
        a = b;
        b = t;
    }
    public static int LCM(int a, int b)
    {
        int c = a * b;
        if (a < b) Swap(ref a, ref b);
        int d = a % b;
        while (d != 0)
        {
            a = b;
            b = d;
            d = a % b;
        }
        return c / b;
    }
    public static string StrReverce(string s)
    {
        return new string(s.Reverse().ToArray());
    }
    public static int IntRead()
    {
        return int.Parse(Console.ReadLine());
    }
    public static bool IsPrime(int n)
    {
        if (n < 2) return false;
        if (n == 2) return true;
        if (n % 2 == 0) return false;

        //double sqrtNum = Math.Sqrt(n);
        for (int i = 3; i < n; i += 2)
        {
            if (n % i == 0) return false;
        }
        return true;
    }
    public static string[] SpRead(char c)
    {
        return Console.ReadLine().Split(c);
    }
    public static long[] LSRead()
    {
        return Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
    }
    public static long Combination(int n, int r)
    {
        if (n == r) return 1;
        return
            Enumerable.Range((n - r + 1), r).ToList().Aggregate((now, next) => now * next) /
            Enumerable.Range(1, r).ToList().Aggregate((now, next) => now * next);
    }
    public static long Permutation(int n, int r)
    {
        if (n == r) return 1;
        return
            Enumerable.Range((n - r), r).ToList().Aggregate((now, next) => now * next);
    }
    public static long LongRead()
    {
        return long.Parse(Console.ReadLine());
    }
    public static long[] LongLine()
    {
        return Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
    }
}