#include <bits/stdc++.h>
using namespace std;
#define pii pair <int,int>
#define f first
#define s second
const int N=1e6+5;
int n,d,m;
pii a[N];
vector <vector <int>> ans;
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> d >> m;
for(int i=1;i<=m;i++){
cin >> a[i].f;
a[i].s=i;
}
sort(a+1,a+1+m);
int l=1,r=N;
while(l<r){
int mid=(l+r)/2;
vector <vector <int>> v;
vector <int> now;
bool ok=true;
for(int i=1;i<=m;i++){
if(v.size()+1>=a[i].f+d){
ok=false;
break;
}
while(v.size()+1<a[i].f){
v.push_back(now);
now.clear();
}
now.push_back(a[i].s);
if(now.size()==mid){
v.push_back(now);
now.clear();
}
}
if(ok){
r=mid;
ans=v;
}
else l=mid+1;
}
cout << l << "\n";
for(int i=0;i<ans.size();i++) ans[i].push_back(0);
while(ans.size()<n){
vector <int> tmp;
tmp.push_back(0);
ans.push_back(tmp);
}
for(auto v:ans){
for(int x:v) cout << x << " ";
cout << "\n";
}
}
/*
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
*/
