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 Java (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
import java.util.stream.Collectors;
import java.io.*;
import java.math.BigDecimal;
import java.nio.charset.StandardCharsets;

public class Main {

	public static void main(String[] args) throws IOException {
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		Main ins = new Main(in);
		ins.calc();
		ins.showResult();
	}

	int H, W;
	int[] a;
	int N;
	int[] cell;
	int[][] result;

	Main(BufferedReader in) throws IOException {
		String[] tokens = in.readLine().split(" ");
		H = Integer.parseInt(tokens[0]);
		W = Integer.parseInt(tokens[1]);
		N = Integer.parseInt(in.readLine());
		a = new int[N];
		tokens = in.readLine().split(" ");
		for (int i = 0; i < N; ++i) {
			a[i] = Integer.parseInt(tokens[i]);
		}
		cell = new int[H * W];
		int index = 0;
		for (int i = 0; i < N; ++i) {
			for (int j = 0; j < a[i]; ++j) {
				cell[index] = i + 1;
				++index;
			}
		}
	}

	void calc() {
		result = new int[H][W];
		for (int i = 0; i < H * W; ++i) {
			int h = i / W;
			int w = i % W;
			if (h % 2 == 1) {
				w = W - 1 - w;
			}
			result[h][w] = cell[i];
		}
	}

	void showResult() {
		for (int i = 0; i < H; ++i) {
			System.out.print(result[i][0]);
			for (int j = 1; j < W; ++j) {
				System.out.print(" " + result[i][j]);
			}
			System.out.println("");
		}
	}
}