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;
#define __ <<" "<<
#define ___ <<" "
#define bash push_back
#define ALL(x) x.begin(),x.end()
//#define int long long

struct IoSetup {
    IoSetup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout <<fixed<<setprecision(12);
        cerr <<fixed<<setprecision(12);
    }
}IoSetup;

typedef long long ll;
typedef pair < int , int >  pii;
static constexpr const signed int INF = 0x3f3f3f3f;
static constexpr const signed long long LINF = 0x3f3f3f3f3f3f3f3fLL;
static constexpr const signed int SMOD = 1000000007;
static constexpr const signed int NMOD = 998244353;
static constexpr const signed int dx[]={1,0,-1,0,1,1,-1,-1};
static constexpr const signed int dy[]={0,-1,0,1,-1,1,-1,1};

inline bool inside(int x,int y,int w,int h){return (x>=0 && y>=0 && x<w && y<h);}
template<class T>bool chmax(T &a, const T &b){return(a=max(a,b))==b;}
template<class T>bool chmin(T &a, const T &b){return(a=min(a,b))==b;}
inline int qp(int a,ll b,int mo){int ans=1;do{if(b&1)ans=1ll*ans*a%mo;a=1ll*a*a%mo;}while(b>>=1);return ans;}

int h, w, n;
vector<int> a;
int m[105][105];

signed main() {

    cin >> h >> w >> n;
    a.resize(n);

    for(int i = 0; i < n; i++) {
        cin >> a[i];
    }
    //a.bash(INF);
    int p = 0, c =  0;
    int y = 0, x = 0;
    bool d = true;
    while(true) {
        if(x==w) break;
        m[y][x] = p + 1;
        c++;
        if(c==a[p]) c = 0, p++;
        if(d) {
            if(y + 1 == h)
                d = false, x++;
            else
                y++;
        }
        else{
            if(y == 0)
                d = true, x++;
            else
                y--;
        }
    }

    for(int i = 0; i < h; i++) {
        for(int j = 0; j < w; j++) {
            cout << m[i][j] << " \n"[j+1 == w];
        }
    }
  
    return 0;
}