#include <bits/stdc++.h>
using namespace std;
typedef int ll;
typedef pair<int, int> pairs;
using vi = vector<ll>;
#define mp make_pair
ll n,d,m;
pair<bool, vector<vi>> isFeasible(const vector<pairs> &jobs, int machineCount) {
vector<vi> schedule(n);
ll reqNum = 0;
for (ll day = 1; day <= n; day++) {
for (ll j = 0; j < machineCount; j++) {
if(jobs[reqNum].first>day)
{
break;
}
if(jobs[reqNum].first+d>=day)
{
schedule[day-1].push_back(jobs[reqNum++].second);
}
else return mp(false, schedule);
if (reqNum == m) return mp(true, schedule);
}
}
return mp(false, schedule);
}
int main()
{
cin.tie(0)->sync_with_stdio(false);
cin >> n >> d >> m;
vector <pairs> jobs(m);
for(int i=0;i<m;i++)
{
cin >> jobs[i].first;
jobs[i].second=i+1;
}
sort(jobs.begin(),jobs.end());
int l =1;
int r =m;
vector<vi> result;
while (l < r) {
int machineNum = l+(r - l) / 2;
pair<bool, vector<vi>> curResult = isFeasible(jobs, machineNum);
if (curResult.first) {
r = machineNum;
result = curResult.second;
}
else
l = machineNum + 1;
}
cout << l << "\n";
for (int i = 0; i < n; i++) {
for (auto &idx : result[i]) cout << idx << " ";
cout << 0 << "\n";
}
}
