#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define all(x) (x).begin(), (x).end()
#define allr(x) (x).rbegin(), (x).rend()
#define vv vector
#define pb push_back
#define ff first
#define ss second
#define ll long long
#define setbits(x) (__builtin_popcountll(x))
#define getUnique(x) sort((x).begin(), (x).end()), (x).erase(unique((x).begin(), (x).end()), (x).end())
template <typename T>
using iset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// *st.find_by_order(i) - i-th element; st.order_of_key(val) - count < val; for multiset : use less<pair<T, int>>
template <typename T>
using maxHeap = priority_queue<T>;
template <typename T>
using minHeap = priority_queue<T, vector<T>, greater<T>>;
const int mod = 1e9 + 7;
const long long inf = 1e18;
vector<pair<int, int>> dir = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}}; // grid
vector<pair<int, int>> dir2 = {{2, 1}, {2, -1}, {-2, 1}, {-2, -1}, {1, 2}, {1, -2}, {-1, 2}, {-1, -2}}; // knight
// lower_bound(arr.begin(), arr.end(), k,[](const pair<int, int>& arrEle, int val) {return arrEle.second < val;});
// upper_bound(arr.begin(), arr.end(), k,[](int val, const pair<int, int>& arrEle) {return val < arrEle.second;});
// sort(arr.begin(), arr.end(),[](const vector<int>& x, const vector<int>& y) {return x[2] < y[2];});
// auto fun = [&](auto &&self, int u, int p)-> void {self(self, v, u)}; // lambda-dfs
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count()); // for random inputs
// int pivot = a[l + RNG() % (r - l + 1)]; // for fast quick-sort
struct my_hash
{
static uint64_t splitmix64(uint64_t x)
{
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const
{
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
// unordered_map<long long, int, my_hash> safe_map;
// gp_hash_table<long long, int, my_hash> safe_htable; // gnu pbds
void solve()
{
int n, d, m;
cin >> n >> d >> m;
vv<int> job[n + 1];
for (int i = 1; i <= m; i++)
{
int x;
cin >> x;
job[x].pb(i);
}
auto pred = [&](int x) -> bool
{
int cnt = 0;
int j = 1;
for (int i = 1; i <= n - d; i++)
{
int k = 0;
if (j < i)
j = i, cnt = 0;
while (k < job[i].size() && j <= n && j <= i + d)
{
cnt++;
k++;
if (cnt == x)
cnt = 0, j++;
}
if (k < job[i].size())
return 0;
}
return 1;
};
int low = 1, high = m;
while (low <= high)
{
int mid = (low + high) / 2;
if (pred(mid))
high = mid - 1;
else
low = mid + 1;
}
vector<int> ans[n + 1];
int j = 1;
for (int i = 1; i <= n - d; i++)
{
int k = 0;
j = max(j, i);
while (k < job[i].size() && j <= n && j <= i + d)
{
ans[j].pb(job[i][k++]);
if (ans[j].size() == low)
j++;
}
}
cout << low << endl;
for (int i = 1; i <= n; i++)
{
for (auto &j : ans[i])
cout << j << " ";
cout << "0\n";
}
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout << fixed << setprecision(10);
int t = 1;
// cin >> t;
// cin.ignore();
while (t-- > 0)
{
solve();
}
return 0;
}
