#include <bits/stdc++.h>
using namespace std;
int n,d,m;
pair<bool,vector<vector<int>>> check(const vector<pair<int,int>> &jobs,int count) {
vector<vector<int>> schedule(n);
int request_num=0;
for (int day=1; day<=n; day++) {
for (int j=0; j<count; j++) {
if (jobs[request_num].first>day) {
break;
}
if (jobs[request_num].first+d>=day) {
schedule[day-1].push_back(jobs[request_num++].second);
}
else {
return make_pair(false,schedule);
}
if (m==request_num) {
return make_pair(true,schedule);
}
}
}
return make_pair(false,schedule);
}
int main() {
cin >> n >> d >> m;
vector<pair<int,int>> jobs(m);
for (int i = 0; i < m; i++) {
int day;
cin >> day;
jobs[i] = make_pair(day,i+1);
}
sort(jobs.begin(),jobs.end());
vector<vector<int>> results;
int lower=1,upper=m;
while (lower<upper) {
int machines=(lower+upper)/2;
pair<bool,vector<vector<int>>> result =check(jobs,machines);
if (result.first) {
upper=machines;
results=result.second;
}
else
lower=machines+1;
}
cout << lower << endl;
for (int i=0; i<n; i++) {
for (int &idx:results[i]) cout << idx << " ";
cout << 0 << endl;
}
}
