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)

#[allow(unused_macros)]
macro_rules! parse_line {
    ( $t:ty ) => (
        {
            let mut line = String::new();
            ::std::io::stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            iter.next().unwrap().parse::<$t>().unwrap()
        }
    );

    ( $( $t:ty), +) => (
        {
            let mut line = String::new();
            ::std::io::stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            ( $(iter.next().unwrap().parse::<$t>().unwrap()),* )
        }
    );
}

#[allow(unused_macros)]
macro_rules! read_line {
    () => (
        {
            let mut line = String::new();
            ::std::io::stdin().read_line(&mut line).unwrap();
            line.pop();
            line
        }
    )
}

#[allow(unused_macros)]
macro_rules! parse_vec {
    ( $t:ty ) => (
        {
            let mut line = String::new();
            ::std::io::stdin().read_line(&mut line).unwrap();
            let iter = line.split_whitespace();
            iter.map(|v| v.parse::<$t>().unwrap()).collect::<Vec<_>>()
        }
    )
}

fn solve(h: usize, w: usize, aa: Vec<usize>) -> Vec<Vec<usize>> {
    let mut ret = vec![vec![0; w]; h];

    let mut i = 0;
    let mut j = 0;
    let mut dright = true;

    for (c,&a) in aa.iter().enumerate() {
        for _ in 0..a {
            let  x = if dright {
                j
            } else {
                w - 1 - j
            };

            ret[i][x] = c+1;
            j+=1;
            if j == w {
                i+=1;
                j=0;
                dright = !dright;
            }
        }
    }
    ret
}

fn main() {
    let (h,w) = parse_line!(usize, usize);
    let _n = parse_line!(usize);

    let aa = parse_vec!(usize);

    let ans = solve(h,w,aa);

    for line in ans {
        println!("{}", line.iter().map(|c| c.to_string()).collect::<Vec<String>>().join(" "));
    }
}

#[test]
fn solve_test() {
    assert_eq!(solve(2,2,vec![2,1,1]),
               vec![vec![1,1],
                    vec![3,2]]);

    assert_eq!(solve(3,5,vec![1,2,3,4,5]),
               vec![vec![1,2,2,3,3],
                    vec![4,4,4,4,3],
                    vec![5,5,5,5,5]]);
}