#include <bits/stdc++.h> //Andrei Alexandru a.k.a Sho10
#define ll long long
#define double long double
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define all(a) (a).begin(), (a).end()
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define pi pair
#define rc(s) return cout<<s,0
#define endl '\n'
#define mod 1000000007
#define PI 3.14159265359
#define MAXN 100005
#define INF 1000000005
#define LINF 1000000000000000005ll
#define CODE_START ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
ll n,d,m;
pair<ll,ll>a[1000005];
ll calc(ll l,ll r){
if(l==r){
return l;
}
ll mid=(l+r)/2,pos=1;
for(ll i=1;i<=n;i++)
{
if(pos<=m&&a[pos].f+d<i){
return calc(mid+1,r);
}
for(ll j=1;j<=mid&&pos<=m&&a[pos].f<=i;j++)
{
pos++;
}
}
if(pos<=m){
return calc(mid+1,r);
}else return calc(l,mid);
}
int32_t main(){
CODE_START;
cin>>n>>d>>m;
for(ll i=1;i<=m;i++)
{
cin>>a[i].f;
a[i].s=i;
}
sort(a+1,a+m+1);
ll ans=calc(1,m),pos=1;
cout<<ans<<endl;
for(ll i=1;i<=n;i++)
{
for(ll j=1;j<=ans&&pos<=m&&a[pos].f<=i;j++)
{
cout<<a[pos].s<<' ';
pos++;
}
cout<<"0"<<endl;
}
}
