#include <bits/stdc++.h>
using namespace std;
#define all(x) begin(x), end(x)
#define mp make_pair
using pi = pair<int, int>;
using vi = vector<int>;
int N, D, M;
pair<bool, vector<vi>> isFeasible(const vector<pi> &jobs, int machineCount) {
vector<vi> schedule(N);
int reqNum = 0;
for (int day = 1; day <= N; day++) {
for (int 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<pi> jobs(M);
for (int i = 0; i < M; i++) {
int day;
cin >> day;
jobs[i] = mp(day, i + 1);
}
sort(all(jobs));
vector<vi> result;
int l = 1, r = M;
while (l < r) {
int machineNum = (l + r) / 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 (int &idx : result[i]) cout << idx << " ";
cout << 0 << "\n";
}
}
