#include <bits/stdc++.h>
using namespace std;
int n, d, m;
bool check(int mid, pair<int, int> arr[]){
int end[mid]; // Tracks when a machine ends its job
for (int i=0; i<mid; i++){
end[i] = 0;
}
int index = 0;
int maxD = 0;
for (int i=0; i<m; i++){
if (index == mid){
index = 0;
}
if (end[index]+1 > arr[i].first){
maxD = max(maxD, end[index]+1-arr[i].first);
end[index]++;
}else{
end[index] = arr[i].first; // No delay
}
index++;
}
return maxD <= d;
}
int main(){
cin.tie(0);ios_base::sync_with_stdio(0);
cin >> n >> d >> m;
pair<int, int> arr[m];
for (int i=0; i<m; i++){
int curr; cin >> curr;
arr[i] = make_pair(curr, i+1);
}
sort(arr, arr+m);
int low = 0;
int high = m;
while (low < high){
int mid = (low + high)/2;
if (check(mid, arr)){
high = mid;
}else{
low = mid+1;
}
}
vector<int> eachDay[n+1];
int e[low];
for (int i=0; i<low; i++){
e[i] = 0;
}
for (int i=0; i<n; i++){
vector<int> temp;
eachDay[i] = temp;
}
for (int i=0, id = 0; i<m; i++, id++){
if (id == low){
id = 0;
}
int requestDay = arr[i].first;
int canDo = e[id]+1;
e[id] = max(requestDay, canDo); // Only does work when the request comes
eachDay[e[id]].push_back(arr[i].second);
}
cout << low << "\n";
for (int i=1; i<=n; i++){
if (eachDay[i].size() != 0){
for (int j : eachDay[i]){
cout << j << " ";
}
}
cout << 0 << "\n";
}
}
