// Wael Benslimene DrStonee
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
template <class T>
using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
const long long mod=1e9+7;
const long long MOD=998244353;
#define ll long long
#define endl '\n'
#define FAST ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define ff first
#define ss second
#define INF 1e18+5
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
ll binpow(ll a,ll b){ll res=1;while(b>0){if(b&1)res=(res*a);a=((a)*(a));b/=2;}return res;}
ll gcd(ll a,ll b){return b==0 ? a:gcd(b,a%b);}
ll lcm(ll a,ll b){return (a/gcd(a,b))*b;}
const int N=1e5+1;
vector<int> v[N],a[N];
void solve()
{
int n,d,m,curr=0;cin>>n>>d>>m;
for(int i=1,x;i<=m;i++)
{
cin>>x;
v[x].pb(i);
curr=max(curr,((int)v[x].size()+d-1) / d);
}
int j=1;
for(int i=1;i<=n;i++)
{
if(v[i].empty())continue;
for(int x=i;x<=d+i;x++)
{
while(!v[i].empty() && (int)a[x].size() < curr)
{
a[x].pb(v[i].back());
v[i].pop_back();
}
}
j=i;
while(!v[i].empty())
{
a[j].pb(v[i].back());
v[i].pop_back();
curr=max(curr,(int)a[j].size());
j++;
if(j>d+i)j=i;
}
}
cout<<curr<<endl;
for(int i=1;i<=n;i++)
{
for(auto x:a[i])
{
cout<<x<<" ";
}
cout<<0<<endl;
}
}
int main()
{
FAST;
int t=1;
// cin>>t;
while(t--)
{
solve();
}
return 0;
}
