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::ops::{Index, IndexMut};
use std::cmp::{Ordering};
use std::collections::BinaryHeap;
// use std::clone::Clone;

fn getline() -> String{
    let mut res = String::new();
    std::io::stdin().read_line(&mut res).ok();
    res
}

macro_rules! split {
    ($x: expr) => {
        ($x).trim().split(' ').collect()
    }
}

macro_rules! parse {
    ($x: expr) => {
        ($x).parse().unwrap()
    }
}

macro_rules! debug {
    ($x: expr) => {
        println!("{}: {}", stringify!($x), $x)
    }
}

fn printvec<T>(v: &Vec<T>) where T: std::fmt::Display {
    for (i,e) in v.into_iter().enumerate() {
        if i != 0 {
            print!(" ");
        }
        print!("{}", e);
    }
    println!();
}

fn main() {
    let s = getline();
    let iv: Vec<_> = split!(s);
    let h: usize = parse!(iv[0]);
    let w: usize = parse!(iv[1]);
    let s = getline();
    let iv: Vec<_> = split!(s);
    let n: usize = parse!(iv[0]);
    let s = getline();
    let iv:Vec<_> = split!(s);
    let a: Vec<i32> = iv.into_iter().map(|x| x.parse().unwrap()).collect(); 
    
    let mut x = 0;
    let mut y = 0;
    let mut ans = vec![vec![0;w];h];
    for i in 0..n {
        for _ in 0..a[i] {
            ans[x][y] = i+1;
            if x%2 == 0 {
                if y == w-1 {
                    x += 1;
                } else {
                    y += 1;
                }
            } else {
                if y == 0 {
                    x += 1;
                } else {
                    y -= 1;
                }
            }
        }
    }
    for e in &ans {
        printvec(e);
    }
}