#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define ar array
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template <typename T>
using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define vt vector
#define pb push_back
#define all(c) (c).begin(), (c).end()
#define sz(x) (int)(x).size()
#define pll pair<ll, ll>
#define F_OR(i, a, b, s) for (int i = (a); (s) > 0 ? i < (b) : i > (b); i += (s))
#define F_OR1(e) F_OR(i, 0, e, 1)
#define F_OR2(i, e) F_OR(i, 0, e, 1)
#define F_OR3(i, b, e) F_OR(i, b, e, 1)
#define F_OR4(i, b, e, s) F_OR(i, b, e, s)
#define GET5(a, b, c, d, e, ...) e
#define F_ORC(...) GET5(__VA_ARGS__, F_OR4, F_OR3, F_OR2, F_OR1)
#define FOR(...) F_ORC(__VA_ARGS__)(__VA_ARGS__)
#define EACH(x, a) for (auto &x : a)
template <class T>
bool umin(T &a, const T &b)
{
return b < a ? a = b, 1 : 0;
}
template <class T>
bool umax(T &a, const T &b)
{
return a < b ? a = b, 1 : 0;
}
ll FIRSTTRUE(function<bool(ll)> f, ll lb, ll rb)
{
while (lb < rb)
{
ll mb = (lb + rb) / 2;
f(mb) ? rb = mb : lb = mb + 1;
}
return lb;
}
ll LASTTRUE(function<bool(ll)> f, ll lb, ll rb)
{
while (lb < rb)
{
ll mb = (lb + rb + 1) / 2;
f(mb) ? lb = mb : rb = mb - 1;
}
return lb;
}
template <class A>
void read(vt<A> &v);
template <class A, size_t S>
void read(ar<A, S> &a);
template <class A, class B>
void read(pair<A, B> &x);
template <class T>
void read(T &x)
{
cin >> x;
}
void read(double &d)
{
string t;
read(t);
d = stod(t);
}
void read(long double &d)
{
string t;
read(t);
d = stold(t);
}
template <class H, class... T>
void read(H &h, T &...t)
{
read(h);
read(t...);
}
template <class A>
void read(vt<A> &x)
{
EACH(a, x)
read(a);
}
template <class A, size_t S>
void read(array<A, S> &x)
{
EACH(a, x)
read(a);
}
template <class A, class B>
void read(pair<A, B> &x)
{
cin >> x.first >> x.second;
}
string to_string(char c)
{
return string(1, c);
}
string to_string(bool b)
{
return b ? "true" : "false";
}
string to_string(const char *s)
{
return string(s);
}
string to_string(string s)
{
return s;
}
string to_string(vt<bool> v)
{
string res;
FOR(sz(v))
res += char('0' + v[i]);
return res;
}
template <size_t S>
string to_string(bitset<S> b)
{
string res;
FOR(S)
res += char('0' + b[i]);
return res;
}
template <class T>
string to_string(T v)
{
bool f = 1;
string res;
EACH(x, v)
{
if (!f)
res += ' ';
f = 0;
res += to_string(x);
}
return res;
}
template <class A, class B>
string to_string(pair<A, B> &x)
{
return to_string(x.first) + ' ' + to_string(x.second);
}
template <class A>
void write(A x)
{
cout << to_string(x);
}
template <class H, class... T>
void write(const H &h, const T &...t)
{
write(h);
write(t...);
}
void print()
{
write("\n");
}
template <class H, class... T>
void print(const H &h, const T &...t)
{
write(h);
if (sizeof...(t))
write(' ');
print(t...);
}
vt<pair<int, int>> v;
vt<vt<int>> ans;
ll n, d, m;
bool check(ll a) {
ans.assign(n, vt<int>());
queue<pll> q;
int t=1, i=0;
while (t<=n) {
int j;
for (j=0; j<a && q.size(); j++) {
if (t>q.front().first) return false;
ans[t-1].pb(q.front().second); q.pop();
}
for (; j<a && v[i].first==t; j++, i++) {
ans[t-1].pb(v[i].second+1);
}
for (; v[i].first==t; i++) {
q.push({t+d, v[i].second+1});
}
t++;
}
return q.size()==0;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
read(n, d, m);
v.resize(m);
FOR(m) {
cin >> v[i].first;
v[i].second=i;
}
sort(all(v));
ll a=FIRSTTRUE(check, 1, m);
check(a);
print(a);
EACH(x, ans) {
EACH(y, x) cout << y << " ";
cout << "0" << endl;
}
}
