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: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1;} return 0;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1;} return 0;}
const long long INFLL = 1LL<<60;
const int INF = 1<<28;
const long long MOD =1000000000+7;
void solve(int a){cout<<( a?"Yes":"No")<<endl;}

int main()
{
	int h,w,n;
	cin >> h >> w>> n;
	int count=0;
	int at=0;
	vector<int>a(n+1,0);
	vector<int> t(n + 1, 0);
	vector<vector<int>>ans(h+1,vector<int>(w+1,0));
	for(int i=0; i<n;i++){
		cin >>a[i];
		t[i]=a[i]+(i==0?0:a[i-1]);
	}
	for(int a=0;a<h;a++){
		for(int b=0;b<w;b++){
			if(a%2==0){
				ans[a][b]=at+1;
			}else{
				ans[a][w-b-1]=at+1;
			}
			count++;
			if(count >=t[at]){
				at++;
			}
		}
	}
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
		cout << ans[i][j]<<((j==w-1)?"\n":" ");

		}

	}
}