#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){
for (int i = 0; i < jobs.size(); i++){
if (((i+1) / num_of_machines) + 1 > jobs[i].first + max_delay){
return false;
}
}
return true;
}
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);
}
/*
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
3 3 4 4 4 5 5 6 6 7 8 8
*/
