#include <bits/stdc++.h>
using namespace std;
int main() {
int n, d, m;
std::cin >> n >> d >> m;
std::vector<std::array<int, 2>> jobs(m);
for (int i = 0; i < m; i++) {
int day;
std::cin >> day;
jobs[i] = {day, i + 1};
}
std::sort(begin(jobs), end(jobs));
std::vector<std::vector<int>> res;
auto is_feasible = [&] (int machine_count) -> std::pair<bool, std::vector<std::vector<int>>> {
std::vector<std::vector<int>> schedule(n);
int req_num = 0;
for (int day = 1; day <= n; day++) {
for (int j = 0; j < machine_count; j++) {
if (jobs[req_num][0] > day) {
break;
}
if (jobs[req_num][0] + d >= day) {
schedule[day - 1].push_back(jobs[req_num++][1]);
} else {
return {false, schedule};
}
if (req_num == m) {
return {true, schedule};
}
}
}
return {false, schedule};
};
int lo = 1, hi = m;
while (lo < hi) {
int machine_num = (lo + hi) / 2;
std::pair<bool, std::vector<std::vector<int>>> curr_result = is_feasible(machine_num);
if (curr_result.first) {
hi = machine_num;
res = curr_result.second;
} else {
lo = machine_num + 1;
}
}
std::cout << lo << '\n';
for (int i = 0; i < n; i++) {
for (int idx : res[i]) {
std::cout << idx << " ";
}
std::cout << 0 << '\n';
}
}
