Problem:
Score : 400 points

Problem Statement

We have a grid with H rows and W columns of squares.
Snuke is painting these squares in colors 1, 2, ..., N.
Here, the following conditions should be satisfied:

For each i (1 ≤ i ≤ N), there are exactly a_i squares painted in Color i. Here, a_1 + a_2 + ... + a_N = H W.

For each i (1 ≤ i ≤ N), the squares painted in Color i are 4-connected. That is, every square painted in Color i can be reached from every square painted in Color i by repeatedly traveling to a horizontally or vertically adjacent square painted in Color i.

Find a way to paint the squares so that the conditions are satisfied.
It can be shown that a solution always exists.

Constraints

1 ≤ H, W ≤ 100

1 ≤ N ≤ H W

a_i ≥ 1

a_1 + a_2 + ... + a_N = H W

Input

Input is given from Standard Input in the following format:

H W
N
a_1 a_2 ... a_N

Output

Print one way to paint the squares that satisfies the conditions.
Output in the following format:

c_{1 1} ... c_{1 W}
:
c_{H 1} ... c_{H W}

Here, c_{i j} is the color of the square at the i-th row from the top and j-th column from the left.

Sample Input 1

2 2
3
2 1 1

Sample Output 1

1 1
2 3

Below is an example of an invalid solution:

1 2
3 1

This is because the squares painted in Color 1 are not 4-connected.

Sample Input 2

3 5
5
1 2 3 4 5

Sample Output 2

1 4 4 4 3
2 5 4 5 3
2 5 5 5 3

Sample Input 3

1 1
1
1

Sample Output 3

1

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::vec::Vec;
use std::cmp::*;

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>().split_whitespace().map(|e| e.parse().ok().unwrap()).collect()
}

fn main() {
  let (hight, wide) = {
    let v: Vec<usize> = read_vec();
    (v[0], v[1])
  };

  let n: usize = read();
  let a: Vec<usize> = read_vec();
  let mut grid: Vec<Vec<usize>> = vec![vec![0; wide]; hight];

  let mut h: usize = 0;
  let mut w: i64 = 0;
  let mut add: i64 = 1;
  let mut color_num = a[0];
  let mut color = 0;

  for h in 0..hight {
    if add == 1 {
      for w in 0..wide {
        if color_num == 0 {
          color += 1;
          color_num = a[color];
        }

        grid[h][w] = color+1;
        color_num -= 1;
      }
      add = -1;
    } else {
      for w in (0..wide).rev() {
        if color_num == 0 {
          color += 1;
          color_num = a[color];
        }

        grid[h][w] = color+1;
        color_num -= 1;
      }

      add = 1;
    }
  }

  for i in 0..hight {
    for j in 0..wide {
      print!("{} ", grid[i][j]);
    }
    println!("");
  }
}