/*
ID: NAMIN
TASK:
LANG: C++
*/
#include <iostream>
#include <numeric>
#include <math.h>
#include <set>
#include <unordered_set>
#include <vector>
#include <string>
#include <algorithm>
#include <math.h>
#include <queue>
#include <fstream>
#include <map>
#include <unordered_map>
#include <iomanip>
#include <deque>
#include <assert.h>
#define gcd __gcd
#define endl "\n"
#define ll long long
using namespace std;
void solve(){
//ifstream cin("milkvisits.in");
//ofstream cout("milkvisits.out");
int n,d,m;
cin >> n >> d >> m;
vector<pair<int,int>> a(m);
for(int i=0;i<m;i++){
cin >> a[i].first;
a[i].second = i;
}
sort(a.begin(),a.end());
int ans = 1;
int l = 1,r = 1e8;
vector<int> day[n];
while(l <= r){
int x = l+(r-l)/2;
bool ok = true;
int cur_day = 1,cur_nb = 0;
vector<int> day_temp[n];
for(int i=0;i<m;i++){
if(cur_day-a[i].first < 0){
cur_day = a[i].first;
cur_nb = 0;
}
else if(cur_nb == x){
cur_day++;
cur_nb = 0;
}
if(cur_day-a[i].first > d){
ok = false;
break;
}
cur_nb++;
day_temp[cur_day-1].push_back(a[i].second+1);
}
if(ok && cur_day <= n){
ans = x;
r = x-1;
for(int i=0;i<n;i++){
day[i] = day_temp[i];
}
}
else
l = x+1;
}
cout << ans << endl;
for(int i=0;i<n;i++){
for(int x : day[i]){
cout << x << ' ';
}
cout << "0\n";
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
int t = 1;
//cin >> t;
while(t--){
solve();
}
return 0;
}
