#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
const uint64_t SEED = chrono::high_resolution_clock::now().time_since_epoch().count();
struct chash {
static uint64_t splitmix64(uint64_t x) {
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
return splitmix64(x + SEED);
}
};
#define int int64_t
constexpr int INF = INT64_MAX;
bool check(vector<int>& days,int d,int machines) {
map<int,int> q;
for (int i = 0; i < days.size(); i++) {
if (days[i] != 0) {
q[i] = days[i];
}
if (q.empty()) {
continue;
}
int oldest = q.begin()->first;
int cur_util = 0;
while (!q.empty() && cur_util < machines) {
int jobs = min(q[oldest],machines - cur_util);
cur_util += jobs;
q[oldest] -= jobs;
if (q[oldest] == 0) {
q.erase(oldest);
}
oldest = q.begin()->first;
}
if (!q.empty() && i - oldest == d) {
return false;
}
}
return true;
}
int32_t main() {
cin.tie(nullptr);
ios_base::sync_with_stdio(false);
int n,d,m;
cin >> n >> d >> m;
vector<int> days(n);
int r = -INF;
map<int,queue<int>> q;
for (int i = 0; i < m; i++) {
int m_i; cin >> m_i;
m_i--;
days[m_i]++;
q[m_i].push(i + 1);
r = max(r,days[m_i]);
}
int l = 1;
while (l < r) {
int m = (l + r) >> 1;
if (check(days,d,m)) {
r = m;
}
else {
l = m + 1;
}
}
cout << l << '\n';
for (int i = 0; i < n; i++) {
int cur_util = 0;
int oldest = q.begin()->first;
while (!q.empty() && cur_util < l) {
int done = min(l - cur_util,(int64_t) q[oldest].size());
for (int j = 0; j < done; j++) {
int job = q[oldest].front();
q[oldest].pop();
cout << job << ' ';
}
cur_util += done;
if (q[oldest].empty()) {
q.erase(oldest);
}
oldest = q.begin()->first;
}
cout << "0\n";
}
}
