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::{BufRead, Write};
use std::io;

fn solve<R: BufRead, W: Write>(mut input: R, mut output: W) {
    let mut s = String::new();
    input.read_line(&mut s).unwrap();
    let mut split = s.split_whitespace();
    let h: usize = split.next().unwrap().parse().unwrap();
    let w: usize = split.next().unwrap().parse().unwrap();
    let mut s = String::new();
    input.read_line(&mut s).unwrap();
    let _: usize = s.trim().parse().unwrap();
    s.clear();
    input.read_line(&mut s).unwrap();
    let a: Vec<usize> = s.split_whitespace().map(|x| x.parse().unwrap()).collect();
    let mut grid = vec![vec![0; w]; h];
    let mut x = 0;
    let mut y = 0;
    let mut index = 0;
    let mut flag = true;
    for (color, i) in a.into_iter().enumerate() {
        for _ in 0..i {
            grid[x][y] = color + 1;
            index += 1;
            if flag {
                if x == h - 1 {
                    y += 1;
                    flag = false;
                } else {
                    x += 1;
                }
            } else {
                if x == 0 {
                    y += 1;
                    flag = true;
                } else {
                    x -= 1;
                }
            }
        }
    }
    for line in grid {
        let text_vec: Vec<_> = line.into_iter().map(|x| x.to_string()).collect();
        writeln!(output, "{}", text_vec.join(" "));
    }
}

fn main() {
    let stdin = io::stdin();
    let stdout = io::stdout();
    solve(stdin.lock(), stdout.lock());
}

#[cfg(test)]
mod tests {
    //     fn test(input: &str, output: &str) {
    //         let mut v: Vec<u8> = Vec::new();
    //         ::solve(input.as_bytes(), &mut v);
    //         assert_eq!(String::from_utf8(v).unwrap(), output);
    //     }

    //     #[test]
    //     fn case1() {
    //         test(
    //             "3
    // 1 10 100\n",
    //             "Yes\n",
    //         );
    //     }
    //     #[test]
    //     fn case2() {
    //         test(
    //             "4
    // 1 2 3 4\n",
    //             "No\n",
    //         );
    //     }
    //     #[test]
    //     fn case3() {
    //         test(
    //             "3
    // 1 4 1\n",
    //             "Yes\n",
    //         );
    //     }
    //     #[test]
    //     fn case4() {
    //         test(
    //             "2
    // 1 1\n",
    //             "No\n",
    //         );
    //     }
    //     #[test]
    //     fn case5() {
    //         test(
    //             "6
    // 2 7 1 8 2 8\n",
    //             "Yes\n",
    //         );
    //     }
}