#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#ifdef LOCAL
#include "debug/debug.hpp"
#else
#define Debug(...) 42
#endif
namespace {
void RunCase([[maybe_unused]] int testcase) {
int n{};
int d{};
int m{};
std::cin >> n >> d >> m;
std::vector<int> day(m);
for (int& d : day) {
std::cin >> d;
--d;
}
std::vector<int> order(m);
std::iota(order.begin(), order.end(), 0);
std::sort(order.begin(), order.end(),
[&day](int i, int j) { return day[i] < day[j]; });
auto make_schedule =
[&](int num_workers) -> std::optional<std::vector<std::vector<int>>> {
std::vector result(n, std::vector<int>());
std::queue<int> active;
int id = 0;
for (int i = 0; i < n; ++i) {
while (id < m && day[order[id]] == i) {
active.push(id++);
}
int processed = 0;
while (!active.empty() && processed < num_workers) {
int index = active.front();
active.pop();
if (day[order[index]] + d < i) {
return std::nullopt;
}
processed += 1;
result[i].push_back(order[index] + 1);
}
}
return result;
};
int low = 0;
int high = m;
std::vector answer(n, std::vector<int>());
while (high - low > 1) {
int mid = (low + high) >> 1;
if (auto schedule = make_schedule(mid); schedule.has_value()) {
high = mid;
answer = std::move(schedule.value());
} else {
low = mid;
}
}
std::cout << high << "\n";
for (int i = 0; i < n; ++i) {
for (int id : answer[i]) {
std::cout << id << " ";
}
std::cout << "0\n";
}
}
void Main() {
int testcases = 1;
// std::cin >> testcases;
for (int tt = 1; tt <= testcases; ++tt) {
RunCase(tt);
}
}
} // namespace
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
Main();
return 0;
}
