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::io::*;
// hは最終的に0未満になってる可能性があることに注意!

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let h: usize = itr.next().unwrap().parse().unwrap();
    let w: usize = itr.next().unwrap().parse().unwrap();
    let n: usize = itr.next().unwrap().parse().unwrap();
    let mut a: Vec<usize> = (0..n)
        .map(|_| itr.next().unwrap().parse().unwrap())
        .collect();

    let mut ans: Vec<Vec<usize>> = vec![vec![0; w]; h];
    let mut idx = 0;

    for i in 0..h {
        if i % 2 == 0 {
            for j in 0..w {
                ans[i][j] = idx + 1;
                a[idx] -= 1;
                if a[idx] == 0 {
                    idx += 1;
                }
            }
        } else {
            for j in (0..w).rev() {
                ans[i][j] = idx + 1;
                a[idx] -= 1;
                if a[idx] == 0 {
                    idx += 1;
                }
            }
        }
    }
    let mut out = Vec::new();

    for i in 0..h {
        for j in 0..w - 1 {
            write!(out, "{} ", ans[i][j]).ok();
        }
        writeln!(out, "{}", ans[i][w - 1]).ok();
    }
    stdout().write_all(&out).unwrap();
}