#include <bits/stdc++.h>
using namespace std;
bool valid(int& num_of_days, int& max_delay, int& num_of_machines, vector<pair<int,int>>& jobs){
int job_index = 0;
for (int day = 1; day <= num_of_days; day++){
int machines_used = 0;
while (machines_used < num_of_machines && job_index < jobs.size() && jobs[job_index].first <= day){
if (jobs[job_index].first + max_delay < day){
return false;
}
machines_used++;
job_index++;
}
if (job_index == jobs.size()){
return true;
}
}
if (job_index == jobs.size()){
return true;
}
return false;
}
int binary_search(int& num_of_days, int& max_delay, vector<pair<int, int>>& jobs){
int lo = 0, hi = jobs.size();
while (lo < hi){
int mid = lo + (hi - lo) / 2;
if (valid(num_of_days, max_delay, mid, jobs)){
hi = mid;
}
else lo = mid + 1;
}
return hi;
}
void print_output(int min_machines, int& num_of_days, vector<pair<int, int>>& jobs){
cout << min_machines << "\n";
vector<vector<int>> day_to_job_index(num_of_days);
for (int i = 0; i < jobs.size(); i++){
int curr_day = ceil((i+1.0) / min_machines);
day_to_job_index[curr_day-1].push_back(jobs[i].second+1);
}
for (int i = 0; i < num_of_days; i++){
for (int j = 0; j < day_to_job_index[i].size(); j++){
cout << day_to_job_index[i][j] << " ";
}
cout << 0 << "\n";
}
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int num_of_days, max_delay, num_of_jobs;
cin >> num_of_days >> max_delay >> num_of_jobs;
vector<pair<int, int>> jobs(num_of_jobs);
for (int i = 0; i < num_of_jobs; i++){
cin >> jobs[i].first;
jobs[i].second = i;
}
sort(jobs.begin(), jobs.end());
print_output(binary_search(num_of_days, max_delay, jobs), num_of_days, jobs);
}
