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::Read;

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_to_string(&mut buf).unwrap();

    let answer = solve(&buf);

    println!("{}", answer);
}

fn solve(input: &str) -> String {
    let mut iterator = input.split_whitespace();

    let h: usize = iterator.next().unwrap().parse().unwrap();
    let w: usize = iterator.next().unwrap().parse().unwrap();

    let n: usize = iterator.next().unwrap().parse().unwrap();

    let mut a: Vec<(usize, usize)> = Vec::new();
    for i in 0..n {
        let ai: usize = iterator.next().unwrap().parse().unwrap();
        a.push((i + 1, ai));
    }

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

    let mut color = 0;
    let mut ai = 0;
    for i in 0..h {
        for j in 0..w {
            if ai == 0 {
                let pair = a.pop().unwrap();
                color = pair.0;
                ai = pair.1;
            }
            if i % 2 == 0 {
                result[i][j] = color;
            } else {
                result[i][w - j - 1] = color;
            }
            ai -= 1;
        }
    }

    let mut output = String::new();
    for i in 0..h {
        let mut line = String::new();
        for j in 0..w {
            line.push_str(&format!("{} ", result[i][j]))
        }
        output.push_str(&format!("{}\n", line.trim()))
    }
    return output.trim().to_string();
}