Problem:
Score : 300 points

Problem Statement

There is a rectangle in a coordinate plane. The coordinates of the four vertices are (0,0), (W,0), (W,H), and (0,H).
You are given a point (x,y) which is within the rectangle or on its border. We will draw a straight line passing through (x,y) to cut the rectangle into two parts. Find the maximum possible area of the part whose area is not larger than that of the other. Additionally, determine if there are multiple ways to cut the rectangle and achieve that maximum.

Constraints

1 \leq W,H \leq 10^9

0\leq x\leq W

0\leq y\leq H

All values in input are integers.

Input

Input is given from Standard Input in the following format:

W H x y

Output

Print the maximum possible area of the part whose area is not larger than that of the other, followed by 1 if there are multiple ways to cut the rectangle and achieve that maximum, and 0 otherwise.

The area printed will be judged correct when its absolute or relative error is at most 10^{-9}.

Sample Input 1

2 3 1 2

Sample Output 1

3.000000 0

The line x=1 gives the optimal cut, and no other line does.

Sample Input 2

2 2 1 1

Sample Output 2

2.000000 1

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;

class Program{

    const long MOD =1000000007;

    static void Main(string[] args)
    {
        // ここにかく
        double[] num = ScanDoubleArray(4);
        double a = num[0];
        double b = num[1];
        double c = num[2];
        double d = num[3];
        Console.Write(a*b/2 + " ");
        Console.Write( ( (2 * c) == a && (2 * d) == b) ? 1 : 0);
        Console.Write("\n");

    }
    

    static int[] ruiseki(int[] array)
    {
        int[] res = new int[array.Length];
        for (int i = 0; i < array.Length; i++)
        {
            if (i==0)
            {
                res[i] = array[i];
            }
            else
            {
                res[i] = res[i - 1] + array[i];
            }
        }
        return res;
    }
    static int Nibutan(long[] array, long k)
    {
        int low = 0 ;
        int high = array.Length-1;
        int mid = high;

        while (low < high)
        {
            mid = (low + high) / 2;
            if(array[mid] >= k) // k以上の最小index.ココを変えるだけ
            {
                high = mid;
            }
            else
            {
                low = mid + 1;
            }
            mid = (low + high) / 2;
        }
        return mid;
    }   

    static int ScanOneInt()
    {
        return int.Parse(Console.ReadLine());
    }

    static long ScanOneLong()
    {
        return long.Parse(Console.ReadLine());
    }

    static string[] ScanStringArray(int lines)
    {
        string[] str = new string[lines];
        for (int i = 0; i < lines; i++)
        {
            str[i] = Console.ReadLine();
        }
        return str;
    }
    static int[] ScanIntArray(int t)
    {
        string[] str = Console.ReadLine().Split(' ');
        int[] ar = new int[t];
        for (int i = 0; i < t; i++)
        {
            ar[i] = int.Parse(str[i]);
        }
        return ar;
    }

    static Tuple<int,int> ScanTuple()
    {
        int[] tmp = ScanIntArray(2);
        return new Tuple<int, int>(tmp[0], tmp[1]);
    }
    static long[] ScanLongArray(int t)
    {
        string[] str = Console.ReadLine().Split(' ');
        long[] ar = new long[t];
        for (int i = 0; i < t; i++)
        {
            ar[i] = long.Parse(str[i]);
        }
        return ar;
    }

    static string[] ScanStringArray()
    {
        return Console.ReadLine().Split(' ');
    }

    static double[] ScanDoubleArray(int t)
    {
        string[] str = Console.ReadLine().Split(' ');
        double[] ar = new double[t];
        for (int i = 0; i < t; i++)
        {
            ar[i] = double.Parse(str[i]);
        }
        return ar;
    }

    static int[,] ScanIntSquareArray(int h, int w)
    {
        int[,] resAr = new int[h, w];
        for (int i = 0; i < h; i++)
        {
            int[] ar = ScanIntArray(w);
            for (int j = 0; j < w; j++)
            {
                resAr[i, j] = ar[j];
            }
        }
        return resAr;
    }


    static int[,] CombModMake()
    {
        int[,] res = new int[2005, 2005];
        for (int i = 0; i < 2005; i++)
        {
            for (int j = 0; j < 2005; j++)
            {
                if (i == 0 || i < j)
                {
                    res[i, j] = 0;
                }
                else if (j == 0 || i == j)
                {
                    res[i, j] = 1;
                }
                else
                {
                    res[i, j] = (res[i - 1, j] + res[i - 1, j - 1]) % (int)MOD;
                }
            }
        }
        return res;
    }

    // int, long両方で出来るGCDを作った
    static T GCD<T>(T a, T b)
    {
        if((dynamic)a % (dynamic)b == 0)
        {
            return b;
        }
        else
        {
            return GCD((dynamic)b, (dynamic)a % (dynamic)b);
        }
    }



}

public class Dijkstra // 書きかけ
{
    private int maxIndex = -1;
    private const long INF = Int64.MaxValue;
}
public class Pair<T,U>: IComparable where T : IComparable<T> where U: IComparable<U>
{
    public T Item1;
    public U Item2;

    public int  CompareTo(object obj)
    {
        Pair<T,U> pair = (Pair<T, U>)obj;
        return Item1.CompareTo(pair.Item1);
    }
    public Pair(T t, U u)
    {
        Item1 = t;
        Item2 = u;
    }

}


// 計算量: Push -> O(logN), Peek -> O(1)。Clear() -> O(logN)
// ToArray()で配列化
public class PriorityQueue<T> where T : IComparable
{
    private IComparer<T> _comparer = null;
    private int _type = 0;
    private T[] _heap;
    private int _sz = 0;
    private int _count = 0;

    /// <summary>
    /// Priority Queue with custom comparer
    /// </summary>
    public PriorityQueue(int maxSize, IComparer<T> comparer)
    {
        _heap = new T[maxSize];
        _comparer = comparer;
    }

    /*
     -> Item: _heap(ヒープを持つ.sizeはmaxSize)
     -> Item: _type -> 0:asc(昇順), 1:desc(降順)
     */
    public PriorityQueue(int maxSize, int type = 0)
    {
        _heap = new T[maxSize];
        _type = type;
    }

    private int Compare(T x, T y)
    {
        if (_comparer != null) return _comparer.Compare(x, y);
        return _type == 0 ? x.CompareTo(y) : y.CompareTo(x);
        // typeが0なら昇順, 1なら降順にソートするCompare
    }

    public void Push(T x)
    {
        _count++;

        //node number
        var i = _sz++;

        while (i > 0)
        {
            //parent node number
            var p = (i - 1) / 2;
            if (Compare(_heap[p], x) <= 0) break;
            _heap[i] = _heap[p];
            i = p;
        }

        _heap[i] = x;
    }

    public T Pop()
    {
        _count--;

        T ret = _heap[0];
        T x = _heap[--_sz];

        int i = 0;
        while (i * 2 + 1 < _sz)
        {
            //children
            int a = i * 2 + 1;
            int b = i * 2 + 2;

            if (b < _sz && Compare(_heap[b], _heap[a]) < 0) a = b;

            if (Compare(_heap[a], x) >= 0) break;

            _heap[i] = _heap[a];
            i = a;
        }

        _heap[i] = x;

        return ret;
    }

    public int Count()  // O(1)
    {
        return _count;
    }

    public T Peek() // O(1)
    {
        return _heap[0];
    }

    public bool Contains(T x)   // O(N)なので注意
    {
        for (int i = 0; i < _sz; i++) if (x.Equals(_heap[i])) return true;
        return false;
    }

    public void Clear()
    {
        while (Count() > 0) Pop();
    }

    public IEnumerator<T> GetEnumerator() // なにこれ
    {
        var ret = new List<T>();

        while (Count() > 0)
        {
            ret.Add(Pop());
        }

        foreach (var r in ret)
        {
            Push(r);
            yield return r;
        }
    }

    public T[] ToArray()
    {
        T[] array = new T[_sz];
        int i = 0;

        foreach (var r in this)
        {
            array[i++] = r;
        }

        return array;
    }
}



public class GenericOperation<T>
{
    public GenericOperation()
    {
        var availableT = new Type[]
        {
            typeof(int), typeof(uint), typeof(short), typeof(ushort), typeof(long), typeof(ulong), typeof(byte),
            typeof(decimal), typeof(double)
        };
        if (!availableT.Contains(typeof(T)))
        {
            throw new NotSupportedException();
        }
        var p1 = Expression.Parameter(typeof(T));
        var p2 = Expression.Parameter(typeof(T));
        Add = Expression.Lambda<Func<T, T, T>>(Expression.Add(p1, p2), p1, p2).Compile();
        Subtract = Expression.Lambda<Func<T, T, T>>(Expression.Subtract(p1, p2), p1, p2).Compile();
        Multiply = Expression.Lambda<Func<T, T, T>>(Expression.Multiply(p1, p2), p1, p2).Compile();
        Divide = Expression.Lambda<Func<T, T, T>>(Expression.Divide(p1, p2), p1, p2).Compile();
        Modulo = Expression.Lambda<Func<T, T, T>>(Expression.Modulo(p1, p2), p1, p2).Compile();
        Equal = Expression.Lambda<Func<T, T, bool>>(Expression.Equal(p1, p2), p1, p2).Compile();
        GreaterThan = Expression.Lambda<Func<T, T, bool>>(Expression.GreaterThan(p1, p2), p1, p2).Compile();
        GreaterThanOrEqual = Expression.Lambda<Func<T, T, bool>>(Expression.GreaterThanOrEqual(p1, p2), p1, p2).Compile();
        LessThan = Expression.Lambda<Func<T, T, bool>>(Expression.LessThan(p1, p2), p1, p2).Compile();
        LessThanOrEqual = Expression.Lambda<Func<T, T, bool>>(Expression.LessThanOrEqual(p1, p2), p1, p2).Compile();
    }

    public Func<T, T, T> Add { get; private set; }
    public Func<T, T, T> Subtract { get; private set; }
    public Func<T, T, T> Multiply { get; private set; }
    public Func<T, T, T> Divide { get; private set; }
    public Func<T, T, T> Modulo { get; private set; }
    public Func<T, T, bool> Equal { get; private set; }
    public Func<T, T, bool> GreaterThan { get; private set; }
    public Func<T, T, bool> GreaterThanOrEqual { get; private set; }
    public Func<T, T, bool> LessThan { get; private set; }
    public Func<T, T, bool> LessThanOrEqual { get; private set; }
}

class Segtree<T>
{
    int n;
    T[] tree;
    Func<T, T, T> f;
    T exnum;
    public Segtree(int m, Func<T, T, T> f, T ex)
    {
        this.f = f;
        exnum = ex;
        n = 1;
        while (n < m) n <<= 1;  // resize calc
        tree = new T[(n << 1) - 1]; // resize
        for (int i = 0; i < tree.Length; i++) tree[i] = ex; // init
    }
    public Segtree(int m, T ini, Func<T, T, T> f, T ex) : this(m, f, ex)
    {
        for (int i = 0; i < m; ++i) tree[i + n - 1] = ini;
        All_update();
    }
    public void Assign_without_update(int j, T x)
    {
        tree[j + n - 1] = x;
    }
    public void Update(int j, T x)
    {
        int i = j + n - 1;
        tree[i] = x;
        while (i > 0)
        {
            i = (i - 1) >> 1;
            tree[i] = f(tree[(i << 1) + 1], tree[(i << 1) + 2]);
        }
    }
    public void All_update()
    {
        for (int i = n - 2; i >= 0; i--)
            tree[i] = f(tree[(i << 1) + 1], tree[(i << 1) + 2]);
    }
    public T Look(int i) { return tree[i + n - 1]; }

    // [s, t)
    public T Run(int s, int t) { return Query(s, t, 0, 0, n); }
    T Query(int s, int t, int k, int l, int r)
    {
        if (r <= s || t <= l) return exnum;
        if (s <= l && r <= t) return tree[k];

        return f(Query(s, t, (k << 1) + 1, l, (l + r) >> 1), Query(s, t, (k + 1) << 1, (l + r) >> 1, r));
    }
}