#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main() {
int n, d, m;
cin >> n >> d >> m;
vector<vector<int>> tarefas(n + 1);
vector<int> entrada_tarefas(m);
for (int i = 0; i < m; ++i) {
cin >> entrada_tarefas[i];
}
for (int i = 0; i < m; ++i) {
tarefas[entrada_tarefas[i]].push_back(i + 1);
}
int l = 1, r = m;
while (l <= r) {
int meio = (l + r) / 2;
bool valido = true;
int pos_dia = 1;
int qtd = 0;
for (int i = 1; i <= n; ++i) {
int val = tarefas[i].size();
if (pos_dia < i) {
pos_dia = i;
qtd = 0;
}
while (val > 0) {
if (pos_dia - i > d) {
valido = false;
break;
}
--val;
++qtd;
if (qtd == meio) {
qtd = 0;
++pos_dia;
}
}
if (!valido) {
break;
}
}
if (valido) {
r = meio - 1;
} else {
l = meio + 1;
}
}
cout << l << endl;
vector<vector<int>> resp(n + 1);
int pos_dia = 1;
int qtd = 0;
for (int i = 1; i <= n; ++i) {
if (pos_dia < i) {
pos_dia = i;
qtd = 0;
}
while (!tarefas[i].empty()) {
++qtd;
resp[pos_dia].push_back(tarefas[i].back());
tarefas[i].pop_back();
if (qtd == l) {
qtd = 0;
++pos_dia;
}
}
}
for (int i = 1; i <= n; ++i) {
for (size_t j = 0; j < resp[i].size(); ++j) {
cout << resp[i][j] << " ";
}
cout << "0" << endl;
}
return 0;
}
