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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h> // uint64_t

#define max(a,b) ((a) > (b) ? (a) : (b))
#define min(a,b) ((a) > (b) ? (b) : (a))

int get_int2(int *a1, int *a2) {
  scanf("%d %d", a1, a2);
  return 0;
}

// <arr[0]> <arr[1]> .. <arr[size-1]>
int fget_array(char *arr, int size) {
    int i;
    for(i = 0; i < size; i++) {
        int n;
        scanf("%d", &n);
        arr[i] = n;
    }
    return 0;
}

#define ROW_MAX 500
#define COL_MAX 500
struct point2d {
    int row;
    int col;
};

static struct point2d stack[ROW_MAX*COL_MAX];
static int sidx = 0;
struct point2d pop(void) {
    return stack[--sidx];
}
void push(struct point2d p) {
    stack[sidx++] = p;
}

#define ANS_MAX 10000000
struct operation {
    struct point2d cur;
    struct point2d next;
};

int move(struct point2d start, struct point2d end, struct operation *out) {
    int i;
    int idx = 0;
    int dir = (end.row-start.row >= 0) ? 1 : -1;
    for(i = start.row; i != end.row; i+=dir) {
        out[idx++] = (struct operation){{i, start.col}, {i+dir, start.col}};
    }
    dir = (end.col-start.col>=0) ? 1 : -1;
    for(i = start.col; i != end.col; i+=dir) {
        out[idx++] = (struct operation){{end.row, i}, {end.row, i+dir}};
    }
    return idx;
}

int main(void) {
    int rs, cs;
    get_int2(&rs, &cs);
    static char map[ROW_MAX+2][COL_MAX+2];
    int i, j;
    for(i = 1; i <= rs; i++) {
        fget_array(&map[i][1], cs);
        for(j = 1; j <= cs; j++) {
            if(map[i][j]%2) push((struct point2d){i, j});
        }
    }

    int cnt = 0;
    static struct operation ops[ANS_MAX];
    int oidx = 0;
    while(sidx > 1) {
        struct point2d start = pop();
        struct point2d end = pop();
#ifdef DEBUG
        printf("%d %d -> %d %d\n", start.row, start.col, end.row, end.col);
#endif
        int c = move(start, end, &ops[oidx]);
        cnt += c;
        oidx += c;
    }

    printf("%d\n", cnt);
    for(i = 0; i < oidx; i++) {
        printf("%d %d %d %d\n",
            ops[i].cur.row, ops[i].cur.col,
            ops[i].next.row, ops[i].next.col
        );
    }

    return 0;

}