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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

int r, c, n, a[10005], ans[105][105];
int dy[] = { 0, 1, 0, -1 };
int dx[] = { 1, 0, -1, 0 };
int main() {
	scanf("%d %d", &r, &c);
	scanf("%d", &n);
	for (int i = 1; i <= n; i++) {
		scanf("%d", &a[i]);
	}
	int y = 0, x = 0, dir=0;

	for (int i = 1; i <= n; i++) {
		while (a[i]) {
			--a[i];
			ans[y][x] = i;
			int ny = y + dy[dir];
			int nx = x + dx[dir];
			if (!(ny >= 0 && ny < r && nx >= 0 && nx < c) || ans[ny][nx]) {
				dir = (dir + 1) % 4;
				ny = y + dy[dir];
				nx = x + dx[dir];
			}
			y = ny, x = nx;
		}
	}
	for (int i = 0; i < r; i++) {
		for (int j = 0; j < c; j++)printf("%d ", ans[i][j]);
		puts("");
	}
}