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 <bits/stdc++.h>
using namespace std;
template <typename T> bool chmax(T &u, const T z) { if (u < z) {u = z; return true;} else return false; }
template <typename T> bool chmin(T &u, const T z) { if (u > z) {u = z; return true;} else return false; }
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ll long long 
//typedef pair<ll, ll> P;
//const ll INF=1LL<<60;
ll gcd(ll x,ll y){return y? gcd(y,x%y) :x;}

int main(){
    int h,w,n;
    cin>>h>>w>>n;
    int masu=h*w;
    vector<int>a(n),b(masu);
    int c[100][100];
    rep(i,n)cin>>a[i];
    int cnt=0;
    int kazu=0;
    rep(i,masu){
        kazu++;
        b[i]=cnt+1;
        if(kazu==a[cnt]){
            cnt++;
            kazu=0;
        }
    }
    int k=0;
    rep(i,h){
        rep(j,w){
            if(i%2==0)c[i][j]=b[k];
            else c[i][w-1-j]=b[k];
            k++;
        }
    }
    rep(i,h){
        rep(j,w){
            cout<<c[i][j]<<" ";
        }
        cout<<endl;
    }
    return 0;
}