#include <bits/stdc++.h>
#if __has_include("debugging.hpp")
#include "debugging.hpp"
#endif
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(NULL);
int day_num;
int max_delay;
int job_num;
cin >> day_num >> max_delay >> job_num;
vector<pair<int, int>> jobs(job_num);
for (int j = 0; j < job_num; j++) {
cin >> jobs[j].first;
jobs[j].first--;
jobs[j].second = j + 1;
}
sort(jobs.begin(), jobs.end());
int lo = 1;
int hi = job_num;
int valid = -1;
vector<vector<int>> sched;
while (lo <= hi) {
int mid = (lo + hi) / 2;
vector<vector<int>> buildup(day_num);
int day_at = 0;
for (const auto& [time, j] : jobs) {
day_at = max(day_at, time);
if (buildup[day_at].size() == mid) {
day_at++;
}
if (day_at - time > max_delay) {
goto bad;
}
buildup[day_at].push_back(j);
}
valid = mid;
hi = mid - 1;
sched = buildup;
continue;
bad:;
lo = mid + 1;
}
cout << valid << '\n';
for (const vector<int>& proc : sched) {
for (int p : proc) {
cout << p << ' ';
}
cout << 0 << '\n';
}
}
