#include <bits/stdc++.h>
using namespace std;
int main()
{
int n, d, m;
//ios::sync_with_stdio(false);
//cin.tie(nullptr);
cin >> n >> d >> m;
vector<int> jobs(m);
unordered_map<int, vector<int>> mp;
unordered_map<int, int> val;
for (int i = 1; i <= m; ++i) {
int a;
cin >> a;
jobs[i - 1] = a;
mp[a].push_back(i);
}
sort(jobs.begin(), jobs.end());
vector<vector<int>> ans;
int l = 1, r = m;
while (l < r) {
int mid = l + (r - l) / 2, start = 0;
//cout << "testing mid: " << mid << "\n";
bool check = true;
vector<vector<int>> jobstmp(n);
for (int i = 0; i < n && check; ++i) {
//cout << i << "\n";
for (int j = 0; j < mid && start <= m - 1; ++j) {
//cout << "bat\n";
if (jobs[start] <= i + 1 && i + 1 - jobs[start] <= d) {
jobstmp[i].push_back(jobs[start]);
++start;
//cout << "at\n";
}
else if (i + 1 - jobs[start] > d) {
check = false;
break;
}
else {
break;
}
}
}
/*for (auto val : jobstmp) {
for (int i : val) {
cout << i << " ";
}
cout << "\n";
}*/
//cout << "start: " << start << " check: " << "\n";
if (check && start == m) {
//cout << "r from " << r << " to r -> " << mid << "\n";
r = mid;
ans = jobstmp;
}
else {
//cout << "l from " << l << " to l -> " << mid << " + 1\n";
l = mid + 1;
}
}
cout << l << "\n";
for (auto i : ans) {
for (int j : i) {
cout << mp[j][val[j]] << " ";
++val[j];
}
cout << "0\n";
}
}
