Problem:
Score : 400 points

Problem Statement

There is a grid of square cells with H horizontal rows and W vertical columns. The cell at the i-th row and the j-th column will be denoted as Cell (i, j).

In Cell (i, j), a_{ij} coins are placed.

You can perform the following operation any number of times:

Operation: Choose a cell that was not chosen before and contains one or more coins, then move one of those coins to a vertically or horizontally adjacent cell.

Maximize the number of cells containing an even number of coins.

Constraints

All values in input are integers.

1 \leq H, W \leq 500

0 \leq a_{ij} \leq 9

Input

Input is given from Standard Input in the following format:

H W
a_{11} a_{12} ... a_{1W}
a_{21} a_{22} ... a_{2W}
:
a_{H1} a_{H2} ... a_{HW}

Output

Print a sequence of operations that maximizes the number of cells containing an even number of coins, in the following format:

N
y_1 x_1 y_1' x_1'
y_2 x_2 y_2' x_2'
:
y_N x_N y_N' x_N'

That is, in the first line, print an integer N between 0 and H \times W (inclusive), representing the number of operations.

In the (i+1)-th line (1 \leq i \leq N), print four integers y_i, x_i, y_i' and x_i' (1 \leq y_i, y_i' \leq H and 1 \leq x_i, x_i' \leq W), representing the i-th operation. These four integers represents the operation of moving one of the coins placed in Cell (y_i, x_i) to a vertically or horizontally adjacent cell, (y_i', x_i').

Note that if the specified operation violates the specification in the problem statement or the output format is invalid, it will result in Wrong Answer.

Sample Input 1

2 3
1 2 3
0 1 1

Sample Output 1

3
2 2 2 3
1 1 1 2
1 3 1 2

Every cell contains an even number of coins after the following sequence of operations:

Move the coin in Cell (2, 2) to Cell (2, 3).

Move the coin in Cell (1, 1) to Cell (1, 2).

Move one of the coins in Cell (1, 3) to Cell (1, 2).

Sample Input 2

3 2
1 0
2 1
1 0

Sample Output 2

3
1 1 1 2
1 2 2 2
3 1 3 2

Sample Input 3

1 5
9 9 9 9 9

Sample Output 3

2
1 1 1 2
1 3 1 4

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

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

namespace AtCoder
{
    class Program
    {
        static int h;
        static int w;
        static int y;
        static int x;

        static void Main(string[] args)
        {
            //[summary]D - Make Them Even
            var items = GetItemsFromReadLines<int>(1).ToList();
            h = items[0][0];
            w = items[0][1];

            //マス目を取得
            var squares = GetItemsFromReadLines<int>(h).ToList();

            //これまでの経緯を保存するためのList
            var positions = new List<List<int>>();

            //過去に選択済みのマス目
            var coordinates = new List<Coordinate>();

            while (true)
            {
                bool isTransport = false;

                for (int i = 0; i < h; i++)
                {
                    for (int j = 0; j < w; j++)
                    {
                        if(coordinates.Count(x => x.PosY == i && x.PosX == j) == 0)
                        {
                            if (squares[i][j] % 2 == 1)
                            {
                                GetTargetPosition(squares, i, j, coordinates);

                                if (y != -1 && x != -1)
                                {
                                    squares[i][j]--;
                                    squares[y][x]++;

                                    var position = new List<int>() { i + 1, j + 1, y + 1, x + 1 };
                                    positions.Add(position);

                                    var coordinate = new Coordinate(i, j);
                                    coordinates.Add(coordinate);
                                    isTransport = true;
                                }
                            }
                        }
                    }
                }

                if (!isTransport)
                {
                    break;
                }
            }

            Console.WriteLine(positions.Count);

            foreach(var pos in positions)
            {
                Console.WriteLine(String.Join(" ", pos));
            }
        }

        static void GetTargetPosition(List<List<int>> squares, int i, int j, 
                                      List<Coordinate> coordinates)
        {
            //上のマス目
            if (i - 1 >= 0)
            {
                if (squares[i - 1][j] % 2 == 1)
                {
                    y = i - 1;
                    x = j;
                    return;
                }
            }

            //下のマス目
            if (i + 1 < h)
            {
                if (squares[i + 1][j] % 2 == 1)
                {
                    y = i + 1;
                    x = j;
                    return;
                }
            }

            //左のマス目
            if (j - 1 >= 0)
            {
                if (squares[i][j - 1] % 2 == 1)
                {
                    y = i;
                    x = j - 1;
                    return;
                }
            }

            //右のマス目
            if (j + 1 < w)
            {
                if (squares[i][j + 1] % 2 == 1)
                {
                    y = i;
                    x = j + 1;
                    return;
                }
            }

            //(まだ選んだことのないマスなら、すでに偶数でもそのマス目に移動する)
            //上のマス目
            if (i - 1 >= 0)
            {
                if (coordinates.Count(x => x.PosY == i - 1 && x.PosX == j) == 0)
                {
                    y = i - 1;
                    x = j;
                    return;
                }
            }

            //下のマス目
            if (i + 1 < h)
            {
                if (coordinates.Count(x => x.PosY == i + 1 && x.PosX == j) == 0)
                {
                    y = i + 1;
                    x = j;
                    return;
                }
            }

            //左のマス目
            if (j - 1 >= 0)
            {
                if (coordinates.Count(x => x.PosY == i && x.PosX == j - 1) == 0)
                {
                    y = i;
                    x = j - 1;
                    return;
                }
            }

            //右のマス目
            if (j + 1 < w)
            {
                if (coordinates.Count(x => x.PosY == i && x.PosX == j + 1) == 0)
                {
                    y = i;
                    x = j + 1;
                    return;
                }
            }

            x = -1;
            y = -1;
        }

        static IEnumerable<List<T>> GetItemsFromReadLines<T>(int count = 0, char separator = ' ')
        {
            //[summary]コンソールの値を読み込んで、List<T>のコレクションを返却

            //読み込む行数が未指定のときは、1行目の値を"count"とみなす
            if (count == 0)
            {
                string line = Console.ReadLine().TrimEnd();
                count = int.Parse(line);
            }
            
            for(int i = 0; i < count; i++)
            {
                //コンソールを1行読み込み
                string line = Console.ReadLine().TrimEnd();

                //読み込んだ値を"separator"で区切る
                var list = line.Split(separator).ToList();

                //int型のときは数値に変換
                if (typeof(T) == typeof(int))
                {
                    var numbers = list.ConvertAll(int.Parse);
                    yield return (List<T>)(object)numbers;
                }
                else
                {
                    yield return (List<T>)(object)list;
                }
            }
        }
    }

    class Coordinate
    {
        public int PosY { set; get; }
        public int PosX { set; get; }

        public Coordinate(int posY, int posX)
        {
            PosY = posY;
            PosX = posX;
        }
    }
}