/*
*
* ^v^
*
*/
#include <iostream>
#include <numeric>
#include <set>
#include <iomanip>
#include <chrono>
#include <queue>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <bitset>
#include <algorithm>
#include <array>
#include <random>
using namespace std;
using ll = int;
using ld = long double;
#define iamtefu ios_base::sync_with_stdio(false); cin.tie(0);
#define fl(i,a,n) for (ll i(a); i<n; i++)
#define rfl(i,a,n) for (ll i(n-1); i>=a; i--)
#define ty int _; for(cin>>_; _--;)
#define print(a) for(auto ele:a){cout<<ele<<" ";}cout<<'\n';
template <typename L, typename R>
inline bool chmax(L &a, R &b){if (a<b){a=b;return 1;}return 0;}
template <typename L, typename R>
inline bool chmin(L &a, R &b){if (a>b){a=b;return 1;}return 0;}
template <typename L, typename R>
ostream& operator<<(ostream &fout, const pair<L, R> &p){
fout<<"{"<<p.first<<","<<p.second<<"}";
return fout;
}
template <typename T>
ostream& operator<<(ostream &fout, const vector <T> &v){
for (auto &x:v){
fout<<x<<" ";
}
fout<<"\n";
return fout;
}
template <typename T>
ostream& operator<<(ostream &fout, const set <T> &st){
for (auto &x:st){
fout<<x<<" ";
}
fout<<"\n";
return fout;
}
template <typename K, typename V>
ostream& operator<<(ostream &fout, const map<K, V> &mp){
fout<<"[";
for (auto &[x,y]:mp){
fout<<x<<":"<<y<<" ";
}
fout<<"]\n";
return fout;
}
ll gcd(ll a, ll b){
if (b==0){
return a;
}
return gcd(b, a%b);
}
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll pw(ll a, ll b, ll m){
ll res=1;
a%=m;
while (b){
if (b&1){
res=(res*a)%m;
}
a=(a*a)%m;
b/=2;
}
return res;
}
void scn(){
ll n, d, m; cin>>n>>d>>m;
vector <ll> a(m);
fl(i,0,m){
cin>>a[i];
}
vector <vector <pair<ll,ll>>> val(n+1);
fl(i,0,m){
val[a[i]].push_back({a[i]+d, i+1});
}
auto bin=[&](ll mid){
priority_queue<ll> pq;
fl(i,1,n+1){
for (auto &x:val[i]){
// cout<<x;
pq.push(-x.first);
}
// cout<<'\n';
if (pq.size() && -pq.top()<i){
return false;
}
ll cur = mid;
while (cur-- && pq.size()){
pq.pop();
}
}
return true;
};
// cout<<bin(1)<<" "<<bin(2)<<'\n';
ll l = 1, r = m+1;
while (l<=r){
ll mid = (l+r)/2;
if (bin(mid)){
r = mid-1;
} else {
l = mid+1;
}
}
cout<<l<<'\n';
priority_queue<pair<ll,ll>> pq;
vector <vector <ll>> ans(n+1);
fl(i,1,n+1){
for (auto x:val[i]){
pq.push({-x.first, x.second});
}
ll cur = l;
while (cur-- && pq.size()){
ans[i].push_back(pq.top().second);
pq.pop();
}
ans[i].push_back(0);
}
fl(i,1,n+1){
fl(j,0,ans[i].size()){
cout<<ans[i][j]<<" \n"[j==(ans[i].size()-1)];
}
}
// not necessarily distinct
// right down
}
int main(){
iamtefu;
#if defined(airths)
auto t1=chrono::high_resolution_clock::now();
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
// ty
{
scn();
}
#if defined(airths)
auto t2=chrono::high_resolution_clock::now();
ld ti=chrono::duration_cast<chrono::nanoseconds>(t2-t1).count();
ti*=1e-6;
cerr<<"Time: "<<setprecision(12)<<ti;
cerr<<"ms\n";
#endif
return 0;
}
