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 (1.42.0) (judge verdict: Accepted)

use proconio::{input, fastout};

macro_rules! echo {
  ($val:expr) => {
    println!("{}", $val);
  }
}

#[fastout]
fn main() {
  input!{
    h: usize,
    w: usize,
    n: usize,
    mut aa: [usize; n]
  };

  let mut ans = vec![vec![0; w]; h];

  let mut idx = 0;
  let forward : Vec<usize> = (0..w).collect();
  let backward : Vec<usize> = (0..w).rev().collect();
  for i in 0..h {
    let range = if i % 2 == 0 {&forward} else {&backward};
    for j in range {
      let j = *j;
      ans[i][j] = idx + 1;
      aa[idx] -= 1;
      if aa[idx] == 0 {
        idx += 1;
      }
    }
  }

  let ans = ans.into_iter()
    .map(|row| 
      row.into_iter().map(|i| i.to_string()).collect::<Vec<_>>().join(" ")
    ).collect::<Vec<_>>().join("\n");
  echo!(ans);
}