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 a[10000];

signed main(){

  int H,W,N;
  cin >> H >> W >> N;
  for(int i = 0; i < N; i++){
    cin >> a[i];
  }

  int ans[H][W] = {};
  int h = 0,w = 0;
  int cnt = 0,res = 0;
  for(int i = 0; i < N; i++){
    for(int j = 0; j < a[i]; j++){
      if(res%2 == 0){
        ans[h][w++] = i+1;
        cnt++;
        if(cnt%W == 0) res++,h++,w = 0;
      }
      else {
        ans[h][(W-1)-w] = i+1;
        w++;
        cnt++;
        if(cnt%W == 0) res++,h++,w = 0;
      }
    }
  }

  for(int i = 0; i < H; i++){
    for(int j = 0; j < W; j++){
      cout << ans[i][j] << " ";
    }
    cout << endl;
  }

  return 0;
}