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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <iostream>
#include <vector>
#include <queue>

using namespace std;

int main() {
  int h, w, n;
  cin >> h >> w >> n;
  vector<int> vec;
  queue<int> qe;
  for (int i = 1; i <= n; ++i) {
    int a;
    cin >> a;
    for (int j = 0; j < a; ++j)
      qe.push(i);
  }

  vector<vector<int>> ans(h, vector<int>(w, 0));
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (i % 2 == 0)
        ans[i][j] = qe.front();
      else
        ans[i][w - j - 1] = qe.front();
      qe.pop();
    }
  }

  for (auto &row : ans) {
    cout << row[0];
    for (int i = 1; i < int(row.size()); ++i)
      cout << " " << row[i];
    cout << endl;
  }
}