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: Runtime Error)

#include<iostream>
using namespace std;
int a[105][105];
	int b[105];
	int H, W, n, i, j, h = 1, w = 1;
int main() {
	

	cin >> H >> W;
	cin >> n;
	for (i = 1;i <= n;i++) {
		cin >> b[i];
	}
	for (i = 1;i <= n;i++) {
		for (j = 1;j <= b[i];j++) {
			if (w > W) {
				w -= W;h++;
			}
			a[h][w] = i;
			w++;
		}
	}
	for (i = 1;i <= H;i++) {
		if(i%2){
			for (j = 1;j <= W;j++) {
				cout << a[i][j]<<" ";
			}
		}else{
			for (j = W;j >= 1;j--) {
				cout << a[i][j] << " ";
			}
		}
		cout << endl;
	}
	return 0;
}