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::*;
use std::str::FromStr;

pub fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

fn main() {
    let h: usize = read();
    let w: usize = read();
    let n: usize = read();
    let mut a: Vec<usize> = vec![];
    let mut map: Vec<Vec<String>> = vec![vec!["0".to_string(); w]; h];
    for _ in 0..n {
        let ai = read();
        a.push(ai);
    }

    let mut is_rev = false;
    let mut colors = vec![];
    for i in 0..a.len() {
        let ai = a[i];
        for _ in 0..ai {
            colors.push(i + 1);
        }
    }

    let mut idx = 0;
    for hi in 0..h {
        if is_rev {
            for wi in (0..w).rev() {
                map[hi][wi] = colors[idx].to_string();
                idx += 1;
            }
        } else {
            for wi in 0..w {
                map[hi][wi] = colors[idx].to_string();
                idx += 1;
            }
        }
        is_rev = !is_rev;
    }
    for i in map {
        println!("{}", i.join(" "));
    }
}