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 <iostream>
#include <algorithm>
#include <cstdlib>
#include <string>
#include <map>
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<n;++i)

int main(){
  ll H,W;
  cin >>H >> W;
  ll N;
  cin >> N;
  ll a[200000]={0},c[200][200]={0};
  //cは出力
  rep(i,N)cin >> a[i];
  ll col=0,row=0;
  bool flag =true;//if(true)left to right
  rep(i,N){
    rep(j,a[i]){
      if(flag){
        c[col][row]=i+1;
        row++;
        if(row==W){
          flag=false;
          row=0;
          col++;
        }
      }else{
        c[col][W-1-row]=i+1;
        row++;
        if(row==W){
          flag=true;
          row=0;
          col++;
        }
      }
    }
  }
  rep(i,H){
    rep(j,W){
      cout << c[i][j] << " ";
    }
    cout << endl;
  }
}