#include <bits/stdc++.h>
using namespace std;
#define sz(x) (int)(x).size()
const int MAXN = 1e5;
const int MAXM = 1e6;
int n, d, m;
pair<int, int> jobs[MAXM];
queue<int> q;
bool check(int machines){
while(!q.empty()) q.pop();
int index = 0;
for(int i = 1; i <= n; i++){
while(index < m && jobs[index].first <= i) {
q.push(jobs[index].first);
index++;
}
for(int j = 0; j < machines; j++){
if(!q.empty()) {
int sent = q.front();
if(i - sent > d) return false;
q.pop();
}
else break;
}
}
return q.empty();
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
cin >> n >> d >> m;
for(int i = 0; i < m; i++) {
cin >> jobs[i].first;
jobs[i].second = i + 1;
}
sort(jobs, jobs + m);
int low = 1, high = INT_MAX;
while (low < high) {
int mid = low + (high - low) / 2;
if (check(mid)) high = mid;
else low = mid + 1;
}
// cout << check(1000000);
cout << low << '\n';
while(!q.empty()) q.pop();
int index = 0;
for(int i = 1; i <= n; i++){
while(index < m && jobs[index].first <= i) {
q.push(jobs[index].second);
index++;
}
for(int i = 0; i < low; i++){
if(!q.empty()) {
int sent = q.front();
cout << sent << ' ';
q.pop();
}
else break;
}
cout << "0\n";
}
return 0;
}
