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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"container/heap"
	"fmt"
	"math"
	"os"
	"strconv"
)

const (
	initialBufSize = 10000
	maxBufSize     = 1000000
	mod            = 1e9 + 7
)

var (
	sc *bufio.Scanner = func() *bufio.Scanner {
		sc := bufio.NewScanner(os.Stdin)
		buf := make([]byte, initialBufSize)
		sc.Buffer(buf, maxBufSize)
		sc.Split(bufio.ScanWords)
		return sc
	}()
)

func main() {
	H := getInt()
	W := getInt()
	M := make([][]int, H)
	for i := 0; i < H; i++ {
		M[i] = make([]int, W)
	}

	for i := 0; i < H; i++ {
		for j := 0; j < W; j++ {
			M[i][j] = getInt()
		}
	}

	//for i := 0; i < H; i++ {
	//	fmt.Println(M[i])
	//}

	var result [][]int

	for i := 0; i < H; i++ {
		for j := 0; j < W; j++ {
			if M[i][j] != 0 {
				continue
			}

			oddCnt := 0
			if i-1 >= 0 && M[i-1][j]%2 == 1 {
				oddCnt++
			}
			if j-1 >= 0 && M[i][j-1]%2 == 1 {
				oddCnt++
			}
			if i+1 < H && M[i+1][j]%2 == 1 {
				oddCnt++
			}
			if j+1 < W && M[i][j+1]%2 == 1 {
				oddCnt++
			}

			if oddCnt >= 2 {
				if i-1 >= 0 && M[i-1][j]%2 == 1 {
					M[i][j]++
					M[i-1][j]--
					result = append(result, []int{i-1, j, i, j})
				}
				if j-1 >= 0 && M[i][j-1]%2 == 1 {
					M[i][j]++
					M[i][j-1]--
					result = append(result, []int{i, j-1, i, j})
				}
				if i+1 < H && M[i+1][j]%2 == 1 {
					M[i][j]++
					M[i+1][j]--
					result = append(result, []int{i+1, j, i, j})
				}
				if j+1 < W && M[i][j+1]%2 == 1 {
					M[i][j]++
					M[i][j+1]--
					result = append(result, []int{i, j+1, i, j})
				}
			}
		}
	}

	//for i := 0; i < H; i++ {
	//	fmt.Println(M[i])
	//}

	for i := 0; i < H; i++ {
		for j := 0; j < W; j++ {
			if M[i][j] % 2 == 0 || M[i][j] < 2 {
				continue
			}

			if i-1 >= 0 && (M[i-1][j] == 0 || M[i-1][j]%2 == 1) {
				M[i][j]--
				M[i-1][j]++
				result = append(result, []int{i, j, i-1, j})
			}
			if j-1 >= 0 && (M[i][j-1] == 0 || M[i][j-1]%2 == 1) {
				M[i][j]--
				M[i][j-1]++
				result = append(result, []int{i, j, i, j-1})
			}
			if i+1 < H && (M[i+1][j] == 0 || M[i+1][j]%2 == 1) {
				M[i][j]--
				M[i+1][j]++
				result = append(result, []int{i, j, i+1, j})
			}
			if j+1 < W && (M[i][j+1] == 0 || M[i][j+1]%2 == 1) {
				M[i][j]--
				M[i][j+1]++
				result = append(result, []int{i, j, i, j+1})
			}
		}
	}

	//for i := 0; i < H; i++ {
	//	fmt.Println(M[i])
	//}

	fmt.Println(len(result))
	for i := 0; i < len(result); i++ {
		fmt.Println(result[i][0]+1, result[i][1]+1, result[i][2]+1, result[i][3]+1)
	}
}

type Graph struct {
	n     int
	edges [][]int
}

func NewGraph(n int) *Graph {
	g := &Graph{
		n:     n,
		edges: make([][]int, n),
	}
	return g
}

func (g *Graph) AddEdge(u, v int) {
	g.edges[v] = append(g.edges[v], u)
	g.edges[u] = append(g.edges[u], v)
}

func dfs(c int, edges [][]int, visited map[int]struct{}) {
	visited[c] = struct{}{}

	for _, v := range edges[c] {
		_, flag := visited[v]
		if flag {
			continue
		}
		dfs(v, edges, visited)
	}
}

func bfs(c int, graph *Graph) {
	next := make([]int, 0)
	next = append(next, c)
	visited := make(map[int]struct{})

	for ; len(next) != 0; {
		u := next[0]
		next = next[1:]
		visited[u] = struct{}{}

		for _, v := range graph.edges[u] {
			_, flag := visited[v]
			if flag {
				continue
			}

			// なにか処理

			next = append(next, v)
		}
	}
}

func getInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func getIntArray(n int) []int {
	array := make([]int, n)
	for i := 0; i < n; i++ {
		array[i] = getInt()
	}
	return array
}

func getString() string {
	sc.Scan()
	return sc.Text()
}

func abs(a int) int {
	return int(math.Abs(float64(a)))
}

func pow(p, q int) int {
	return int(math.Pow(float64(p), float64(q)))
}

func powMod(n, p int) int {
	if p == 0 {
		return 1
	} else if p%2 == 0 {
		t := powMod(n, p/2)
		return calcMod(t * t)
	} else {
		return calcMod(n * powMod(n, p-1))
	}
}

func min(nums ...int) int {
	if len(nums) == 0 {
		panic("funciton min() requires at least one argument.")
	}
	res := nums[0]
	for i := 0; i < len(nums); i++ {
		res = int(math.Min(float64(res), float64(nums[i])))
	}
	return res
}

func max(nums ...int) int {
	if len(nums) == 0 {
		panic("funciton max() requires at least one argument.")
	}
	res := nums[0]
	for i := 0; i < len(nums); i++ {
		res = int(math.Max(float64(res), float64(nums[i])))
	}
	return res
}

func strSearch(a []string, b string) bool {
	for i := 0; i < len(a); i++ {
		if a[i] == b {
			return true
		}
	}
	return false
}

func printIntArray(array []int) {
	strArray := fmt.Sprint(array)
	fmt.Println(strArray[1 : len(strArray)-1])
}

func calcMod(x int) int {
	return x % mod
}

func reverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}
	return string(runes)
}

func isPrime(n int) bool {
	if n < 2 {
		return false
	} else if n == 2 {
		return true
	} else if n%2 == 0 {
		return false
	}

	sqrtN := int(math.Sqrt(float64(n)))
	for i := 3; i <= sqrtN; i += 2 {
		if n%i == 0 {
			return false
		}
	}

	return true
}

func contains(s []int, e int) bool {
	for _, v := range s {
		if e == v {
			return true
		}
	}
	return false
}

func makeRange(min, max int) []int {
	a := make([]int, max-min+1)
	for i := range a {
		a[i] = min + i
	}
	return a
}

func powerset2(nums []int) [][]int {
	length := int(math.Pow(2, float64(len(nums))))
	result := make([][]int, length)

	index := 0
	result[index] = []int{}
	index++

	for _, n := range nums {
		max := index
		for i := 0; i < max; i++ {
			result[index] = copyAndAppend(result[i], n)
			index++
		}
	}

	return result
}

func copyAndAppend(nums []int, n int) []int {
	dst := make([]int, len(nums)+1)
	copy(dst, nums)
	dst[len(nums)] = n
	return dst
}

func calcGcd(x, y int) int {
	if y == 0 {
		return x
	} else if x >= y {
		return calcGcd(y, x%y)
	} else {
		return calcGcd(x, y%x)
	}
}

func getDivisor(n int) []int {
	var divisor []int
	divisor = append(divisor, 1)
	if n != 1 {
		divisor = append(divisor, n)
	}

	sqrt := int(math.Sqrt(float64(n)))
	for i := 2; i <= sqrt; i++ {
		if n%i == 0 {
			divisor = append(divisor, i)
			divisor = append(divisor, n/i)
		}
	}
	return divisor
}

type intHeap []int

func (h intHeap) Len() int {
	return len(h)
}

func (h intHeap) Less(i, j int) bool {
	return h[i] > h[j]
}

func (h intHeap) Swap(i, j int) {
	h[i], h[j] = h[j], h[i]
}

func (h *intHeap) Push(x interface{}) {
	*h = append(*h, x.(int))
}

func (h *intHeap) Pop() interface{} {
	old := *h
	n := len(old)
	x := old[n-1]
	*h = old[0 : n-1]
	return x
}

func initHeap() *intHeap {
	ih := &intHeap{}
	heap.Init(ih)
	return ih
}

func (h *intHeap) pushHeap(n int) {
	heap.Push(h, n)
}

func (h *intHeap) popHeap() int {
	return heap.Pop(h).(int)
}

func factMod(n int) int {
	value := 1
	for ; n > 1; n-- {
		value = calcMod(value * n)
	}
	return value
}

func combinationMod(n, k int) int {
	factN := factMod(n)
	factK := factMod(k)
	factNK := factMod(n - k)
	factKR := powMod(factK, mod-2)
	factNKR := powMod(factNK, mod-2)
	return calcMod(factN * calcMod(factKR*factNKR))
}