#include <iostream>
#include <algorithm>
#include <string>
#include <cmath>
#include <set>
#include <array>
#include <cstdio>
#include <vector>
#include <string>
#include <fstream>
#include <tuple>
#include <numeric>
#include <map>
#include <iomanip>
#include <math.h>
#include <queue>
#include <sstream>
#include <stack>
#include <initializer_list>
#include <functional>
#include <cstring>
std::vector<std::pair<int, int>> jobs;
std::vector<int> days;
int n, d, m;
bool solve(int mid) {
std::vector<int> ds = days;
int i = 1;
for (int day = 1; day <= n; day++) {
int count = mid;
if (i < day - d) {
return false;
} else {
while (i <= day && count > 0) {
int dif = std::min(count, ds[i]);
count -= dif;
ds[i] -= dif;
if (ds[i] == 0) {
i++;
}
}
while (i <= n && ds[i] == 0) {
i++;
}
}
}
if (i == n + 1) {
return true;
} else {
return false;
}
}
void print(int r) {
std::cout << r << "\n";
int cur = 0;
for (int i = 1; i <= n; i++) {
for (int j = 0; j < r; j++) {
if (cur < m && jobs[cur].first <= i) {
std::cout << jobs[cur].second << " ";
cur++;
} else {
break;
}
}
std::cout << 0 << "\n";
}
}
int main() {
std::ios_base::sync_with_stdio(0);
std::cin.tie(0);
//freopen("shuffle.in", "r", stdin);
//freopen("shuffle.out", "w", stdout);
std::cin >> n >> d >> m;
jobs.resize(m);
for (int i = 0; i < m; i++) {
std::cin >> jobs[i].first;
jobs[i].second = i + 1;
}
std::sort(jobs.begin(), jobs.end());
days.resize(n + 1);
for (int i = 0; i < m; i++) {
days[jobs[i].first]++;
}
int l = 0;
int r = m;
while (r > l + 1) {
int mid = (l + r) / 2;
if (solve(mid)) {
r = mid;
} else {
l = mid;
}
}
print(r);
return 0;
}
