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 Rust (1.15.1) (judge verdict: Accepted)

// ternary operation
#[allow(unused_macros)]
macro_rules! _if {
  ($_test:expr, $_then:expr, $_else:expr) => {
    if $_test { $_then } else { $_else }
  };
  ($_test:expr, $_pat:pat, $_then:expr, $_else:expr) => {
    match $_test {
      $_pat => $_then,
      _     => $_else
    }
  };
}

use std::io::{ stdin, stdout, Write };
use my::WriteWith;

use std::io::Read;

#[inline(always)]
fn abc109_d() {
  let stdin  = stdin();
  let stdout = stdout();
  let (mut reader, mut writer) = my::rw(500 * 2, stdin.lock(), stdout.lock());
  let mut itoa = my::ItoA::with_capacity(10);

  let h = my::atoui::<usize>(reader.read_until(my::SP));
  let w = my::atoui::<usize>(reader.read_until(my::LF));

  let mut ans = Vec::with_capacity(h * w - 1);

  let mut odd = 0;
  let mut x   = 0;
  let mut y   = 0;

  // let mut reader = reader.into_inner();
  // let mut buf = Vec::with_capacity(w * 2);
  // buf.resize(w * 2, 0);

  for i in 0..h {
    // reader.read(&mut buf).unwrap();
    let buf = reader.read_until(my::LF);
// p!(buf);

    if i % 2 == 0 {
      for j in 0..w {
        if odd != 0 {
          ans.push([y, x, i, j]);
        }
        odd ^= buf[j * 2] & 1;
        y = i;
        x = j;
      }
    } else {
      for mut j in 0..w {
        j = w - 1 - j;

        if odd != 0 {
          ans.push([y, x, i, j]);
        }
        odd ^= buf[j * 2] & 1;
        y = i;
        x = j;
      }
    }
  }

  writer.write_with(itoa.from_usize(ans.len()), b"\n").unwrap();
  for v in &ans {
    writer.write_with(itoa.from_usize(v[0] + 1), b" ").unwrap();
    writer.write_with(itoa.from_usize(v[1] + 1), b" ").unwrap();
    writer.write_with(itoa.from_usize(v[2] + 1), b" ").unwrap();
    writer.write_with(itoa.from_usize(v[3] + 1), b"\n").unwrap();
  }
  writer.flush().unwrap();
}

fn main() {
  abc109_d();
}

//------------------------------------------------------------------------
mod my {
  use std::hash::Hasher;
  use std::hash::BuildHasher;

  pub struct MyHasher(u64);

  impl Default for MyHasher {
    #[inline(always)]
    fn default() -> Self {
      MyHasher(0x00)
    }
  }

  impl BuildHasher for MyHasher {
    type Hasher = MyHasher;

    #[inline(always)]
    fn build_hasher(&self) -> Self::Hasher {
      Self::Hasher::default()
    }
  }

  impl Hasher for MyHasher {
    #[inline(always)]
    fn finish(&self) -> u64 {
      self.0
    }

    #[inline(always)]
    fn write(&mut self, bytes: &[u8]) {
      self.0 = 0;
      for i in 0..bytes.len() {
        self.0 ^= (bytes[i] as u64) << (8 * (i % 8));
      }
    }
  }

  //----------------------------------------------------------------------
  use std::io::{ self, BufRead, BufReader, Write, BufWriter };
  use std::fmt::Debug;
  use std::ops::{ Add, Sub, Mul, Rem, Neg };
  use std::mem;

  const PLUS_SIGN : u8 = b'+';
  const MINUS_SIGN: u8 = b'-';
  const ASCII_0   : u8 = b'0';
  const ASCII_9   : u8 = b'9';

  #[allow(dead_code)]
  pub const SP    : u8 = b' ';
  #[allow(dead_code)]
  pub const LF    : u8 = b'\n';

  //----------------------------------------------------------------------
  #[allow(dead_code)]
  #[inline(always)]
  pub fn rotate_right<T>(ary: &mut [T])
    where T: Copy +
             Debug
  {
    if ary.len() <= 1 {
      return;
    }

    let len = ary.len() - 1;
    let tmp = ary[len];
    for i in 0..len {
      ary[len - i] = ary[len - i - 1];
    }
    ary[0] = tmp;
  }

  #[allow(dead_code)]
  #[inline(always)]
  pub fn rotate_left<T>(ary: &mut [T])
    where T: Copy +
             Debug
  {
    if ary.len() <= 1 {
      return;
    }

    let len = ary.len() - 1;
    let tmp = ary[0];
    for i in 0..len {
      ary[i] = ary[i + 1];
    }
    ary[len] = tmp;
  }

  //----------------------------------------------------------------------
  #[allow(dead_code)]
  #[inline(always)]
  pub fn gcd<T>(mut x: T, mut y: T) -> T
    where T: Rem<Output=T> +
             Default +
             PartialEq +
             Copy +
             Debug
  {
    let zero = T::default();

    if x == zero { return y; }
    if y == zero { return x; }

    while y != zero {
      let tmp = x % y;
      x = y;
      y = tmp;
    }

    x
  }

  //----------------------------------------------------------------------
  #[allow(dead_code)]
  #[inline(always)]
  pub fn intersection<T>(mut x: (T, T), mut y: (T, T)) -> Option<(T, T)>
    where T: PartialOrd +
             Copy +
             Debug
  {
    if x.0 > x.1 {
      mem::swap(&mut x.0, &mut x.1);
    }
    if y.0 > y.1 {
      mem::swap(&mut y.0, &mut y.1);
    }

    if x.0 >= y.1 || x.1 <= y.0 {
      return None;
    }

    if x.0 < y.0 {
      x.0 = y.0;
    }
    if x.1 > y.1 {
      x.1 = y.1;
    }

    Some(x)
  }

  //----------------------------------------------------------------------
  #[allow(dead_code)]
  #[inline(always)]
  pub fn is_ascii_digit(b: u8) -> bool {
    _if!(b >= ASCII_0 && b <= ASCII_9,
      true,
      false)
  }

  #[allow(dead_code)]
  #[inline(always)]
  pub fn is_ascii_uppercase(b: u8) -> bool {
    _if!(b >= b'A' && b <= b'Z',
      true,
      false)
  }

  #[allow(dead_code)]
  #[inline(always)]
  pub fn is_ascii_lowercase(b: u8) -> bool {
    _if!(b >= b'a' && b <= b'z',
      true,
      false)
  }

  #[allow(dead_code)]
  #[inline(always)]
  pub fn is_ascii_alphabetic(b: u8) -> bool {
    _if!(is_ascii_uppercase(b) || is_ascii_lowercase(b),
      true,
      false)
  }

  #[allow(dead_code)]
  #[inline(always)]
  pub fn to_ascii_lowercase(b: u8) -> u8 {
    _if!(is_ascii_uppercase(b),
      b + 0x20,
      b)
  }

  #[allow(dead_code)]
  #[inline(always)]
  pub fn to_ascii_uppercase(b: u8) -> u8 {
    _if!(is_ascii_lowercase(b),
      b - 0x20,
      b)
  }

  //----------------------------------------------------------------------
  #[allow(dead_code)]
  #[inline(always)]
  pub fn atoui<T>(s: &[u8]) -> T
    where T: Add<Output=T> +
             Sub<Output=T> +
             Mul<Output=T> +
             Default +
             From<u8> +
             Debug
  {
    let mut n = T::default();
    if s.len() == 0 {
      return n;
    }

    let mut i = 0;
    if s[i] == PLUS_SIGN {
      i += 1;
    }

    for b in &s[i..] {
      n = (n * T::from(10)) + T::from(b - ASCII_0);
    }

    n
  }

  #[allow(dead_code)]
  #[inline(always)]
  pub fn atoi<T>(s: &[u8]) -> T
    where T: Add<Output=T> +
             Sub<Output=T> +
             Mul<Output=T> +
             Neg<Output=T> +
             Default +
             From<u8> +
             Debug
  {
    let mut n = T::default();
    if s.len() == 0 {
      return n;
    }

    let mut i = 0;
    let mut negative = false;
    if s[i] == MINUS_SIGN {
      negative = true;
      i += 1;
    } else if s[i] == PLUS_SIGN {
      i += 1;
    }

    for b in &s[i..] {
      n = (n * T::from(10)) + T::from(b - ASCII_0);
    }

    _if!(negative,
      n.neg(),
      n)
  }

  //----------------------------------------------------------------------
  #[allow(dead_code)]
  #[inline(always)]
  pub fn rw<R, W>(cap: usize, r: R, w: W) -> (Reader<BufReader<R>>, BufWriter<W>)
    where R: BufRead,
          W: io::Write
  {
    (
      Reader::with_capacity(cap, BufReader::new(r)),
      BufWriter::new(w)
    )
  }

  //----------------------------------------------------------------------
  pub trait WriteWith {
    fn write_with(&mut self, buf: &[u8], delim: &[u8]) -> io::Result<usize>;
  }

  impl<W> WriteWith for BufWriter<W>
    where W: io::Write
  {
    #[allow(dead_code)]
    #[inline(always)]
    fn write_with(&mut self, buf: &[u8], delim: &[u8]) -> io::Result<usize>
    {
      Ok(self.write(buf)? + self.write(delim)?)
    }
  } // impl<W> WriteWith for BufWriter<W>

  //----------------------------------------------------------------------
  macro_rules! pub_fn_ItoA_from_ty {
    (uint, $($name:ident => $_type:ty),*) => {$(
      #[allow(dead_code)]
      #[inline(always)]
      pub fn $name(&mut self, mut n: $_type) -> &[u8] {
        self.buf.clear();
        if n == 0 {
          self.buf.push(ASCII_0);
          return self.buf.as_slice();
        }

        while n > 0 {
          self.buf.push((n % 10) as u8 + ASCII_0);
          n /= 10;
        }
        self.buf.reverse();
        self.buf.as_slice()
      }
    )*};

    (int, $($name:ident => $_type:ty),*) => {$(
      #[allow(dead_code)]
      #[inline(always)]
      pub fn $name(&mut self, mut n: $_type) -> &[u8] {
        self.buf.clear();
        if n == 0 {
          self.buf.push(ASCII_0);
          return self.buf.as_slice();
        }

        let mut negative = false;
        if n.is_negative() {
          negative = true;
          n = n.abs();
        }

        while n > 0 {
          self.buf.push((n % 10) as u8 + ASCII_0);
          n /= 10;
        }
        if negative {
          self.buf.push(MINUS_SIGN);
        }
        self.buf.reverse();
        self.buf.as_slice()
      }
    )*};
  }

  #[derive(Debug)]
  pub struct ItoA {
    buf: Vec<u8>,
  }

  impl ItoA {
    #[allow(dead_code)]
    #[inline(always)]
    pub fn with_capacity(cap: usize) -> Self {
      ItoA {
        buf: Vec::with_capacity(cap),
      }
    }

    pub_fn_ItoA_from_ty!(
      uint,
      from_usize => usize,
      from_u8    => u8,
      from_u16   => u16,
      from_u32   => u32,
      from_u64   => u64
    );

    pub_fn_ItoA_from_ty!(
      int,
      from_isize => isize,
      from_i8    => i8,
      from_i16   => i16,
      from_i32   => i32,
      from_i64   => i64
    );
  } // impl ItoA

  //----------------------------------------------------------------------
  #[derive(Debug)]
  pub struct Reader<R> {
    reader: R,
    buf   : Vec<u8>,
  }

  impl<R> Reader<R>
    where R: BufRead
  {
    #[allow(dead_code)]
    #[inline(always)]
    pub fn with_capacity(cap: usize, reader: R) -> Self {
      Reader {
        reader: reader,
        buf   : Vec::with_capacity(cap),
      }
    }

    #[allow(dead_code)]
    #[inline(always)]
    pub fn into_inner(self) -> R {
      self.reader
    }

    //--------------------------------------------------------------------
    #[allow(dead_code)]
    #[inline(always)]
    pub fn read_until(&mut self, delim: u8) -> &[u8] {
      self.buf.clear();
      let mut len = self.reader.read_until(delim, &mut self.buf).unwrap();
      if len == 0 {
        return &self.buf;
      }

      len -= 1;
      if self.buf[len] == delim {
        self.buf.truncate(len);
      }
      &self.buf
    }

    //--------------------------------------------------------------------
    #[allow(dead_code)]
    #[inline(always)]
    pub fn for_each<F>(&mut self, n: usize, delim: u8, mut func: F)
      where F: FnMut(&[u8])
    {
      for _ in 0..n - 1 {
        func(self.read_until(delim));
      }
      func(self.read_until(LF))
    }

    #[allow(dead_code)]
    #[inline(always)]
    pub fn fold<B, F>(&mut self, n: usize, delim: u8, mut init: B, mut func: F) -> B
      where F: FnMut(B, &[u8]) -> B
    {
      for _ in 0..n - 1 {
        init = func(init, self.read_until(delim));
      }
      func(init, self.read_until(LF))
    }
  } // impl<R> Reader<R>

} // mod my