#include "iostream"
#include "vector"
#include "algorithm"
#include "queue"
#include "set"
#include "unordered_set"
#include "stack"
#include "map"
#include "limits.h"
#include "cstdio"
#include "math.h"
#include <iomanip>
#include <numeric>
using namespace std;
int N,D,M;
pair<bool,vector<vector<int>>> works(const vector<pair<int,int>> &jobs, int machines)
{
vector<vector<int>> schedule(N);
int reqnum = 0;
for(int day = 1; day<=N; day++)
{
for(int j = 0; j<machines; j++)
{
if(jobs[reqnum].first>day)break;
if(jobs[reqnum].first+D>=day)
schedule[day-1].push_back(jobs[reqnum++].second);
else
return make_pair(false,schedule);
if(reqnum==M)
return make_pair(true,schedule);
}
}
return make_pair(false,schedule);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>N>>D>>M;
vector<pair<int,int>> jobs(M);
for(int i = 0; i<M; i++)
{
int day;
cin>>day;
jobs[i]=make_pair(day,i+1);
}
sort(jobs.begin(),jobs.end());
vector<vector<int>> result;
int l = 1; int r= M;
while(l<r)
{
int mid = (l+r)/2;
pair<bool,vector<vector<int>>> res = works(jobs,mid);
if(res.first == true)
{
r = mid;
result = res.second;
}
else
l = mid+1;
}
cout<<l<<endl;
for(int i = 0; i<N; i++)
{
for(auto x: result[i])
{
cout<<x<<" ";
}
cout<<0<<endl;
}
}
