#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1e5 + 1;
int n, d, m;
vector<pair<int, int>> jobs;
pair<bool, vector<vector<int>>> valid(int num) {
vector<vector<int>> sched(n);
int cnt = 0;
for (int i = 1; i <= n; ++i) {
for (int j = 0; j < num; ++j) {
if (jobs[cnt].first > i) {
break;
}
if (jobs[cnt].first + d >= i) {
sched[i - 1].push_back(jobs[cnt++].second);
}
else {
return {false, sched};
}
if (cnt == m) {
return {true, sched};
}
}
}
return {false, sched};
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> d >> m;
jobs.resize(m);
for (int i = 0; i < m; ++i) {
cin >> jobs[i].first;
jobs[i].second = i + 1;
}
sort(jobs.begin(), jobs.end());
vector<vector<int>> sched;
int lo = 1, hi = m;
while (lo < hi) {
int mid = lo + (hi - lo) / 2;
pair<bool, vector<vector<int>>> cur = valid(mid);
if (cur.first) {
hi = mid;
sched = cur.second;
}
else {
lo = mid + 1;
}
}
cout << lo << '\n';
for (int i = 0; i < n; ++i) {
for (int j : sched[i]) {
cout << j << ' ';
}
cout << "0\n";
}
return 0;
}
