#include<iostream>
#include<vector>
#include<map>
#include<set>
#include<cassert>
#include<cassert>
#include<unordered_map>
#include<unordered_set>
#include<functional>
#include<queue>
#include<stack>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<sstream>
#include<iomanip>
#include<cstdio>
#include<cstdlib>
#include<numeric>
#include<random>
#include<chrono>
#include<bitset>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define xx first
#define yy second
#define sz(x) (int)(x).size()
#define gc getchar
#define IO ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define mp make_pair
#ifndef ONLINE_JUDGE
# define LOG(x) (cerr << #x << " = " << (x) << endl)
#else
# define LOG(x) ((void)0)
#endif
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
const double PI=3.1415926535897932384626433832795;
const ll INF = 1LL<<62;
const ll MINF = -1LL<<62;
template<typename T> T getint() {
T val=0;
char c;
bool neg=false;
while((c=gc()) && !(c>='0' && c<='9')) {
neg|=c=='-';
}
do {
val=(val*10)+c-'0';
} while((c=gc()) && (c>='0' && c<='9'));
return val*(neg?-1:1);
}
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); uniform_int_distribution<int>(0, n-1)(rng)
int n,m,d;
vector<pair<int,int>> lst;
vector<int> ans[100001];
bool nemlehet(int x) {
int day=1, akt=0;
for(int i=0;i<sz(lst);++i) {
//cerr<<day<<" "<<akt<<"\n";
if(akt==x) {
day++;
akt=0;
}
if(lst[i].xx>day) {
day=lst[i].xx;
akt=0;
}
if(day-lst[i].xx>d) {
return true;
}
akt++;
}
return day>n;
}
void construct(int x) {
int day=1, akt=0;
for(int i=0;i<sz(lst);++i) {
if(akt==x) {
day++;
akt=0;
}
if(lst[i].xx>day) {
day=lst[i].xx;
akt=0;
}
assert(day<=n);
ans[day].pb(lst[i].yy);
akt++;
}
}
int main() {
IO;
cin>>n>>d>>m;
lst.resize(m);
for(int i=0;i<m;++i) {
cin>>lst[i].xx;
lst[i].yy=i+1;
}
sort(lst.begin(), lst.end());
int akt=0;
for(int i=20;i>=0;i--) {
int curr=akt+(1<<i);
if(nemlehet(curr)) {
akt=curr;
}
}
akt++;
cout<<akt<<"\n";
construct(akt);
for(int i=1;i<=n;++i) {
for(auto j:ans[i]) {
cout<<j<<" ";
}cout<<"0\n";
}
return 0;
}
