#include <bits/stdc++.h>
#define DIM 1000010
#define DIMN 100010
using namespace std;
priority_queue <int,vector<int>,greater<int> > h;
pair <int,int> v[DIM];
vector <int> ans[DIMN];
int n,d,m,i;
int main (){
//ifstream cin ("date.in");
//ofstream cout ("date.out");
cin>>m>>d>>n;
for (i=1;i<=n;i++){
cin>>v[i].first;
v[i].second = i;
}
sort (v+1,v+n+1);
h.push(1);
for (i=1;i<=n;i++){
int day = h.top();
if (day > v[i].first + d){
/// mai adaug o masina
h.push(v[i].first+1);
ans[v[i].first].push_back(v[i].second);
} else {
h.pop();
ans[max(day,v[i].first)].push_back(v[i].second);
h.push(max(day+1,v[i].first+1));
}
}
cout<<h.size()<<"\n";
for (i=1;i<=m;i++){
for (auto it : ans[i])
cout<<it<<" ";
cout<<"0\n";
}
return 0;
}
