// Source: https://usaco.guide/general/io
#include <bits/stdc++.h>
#include <climits>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef long double ld;
typedef pair<ll, ll> pll;
#define FOR(i, a, b) for(int i = a; i < b; i++)
#define ROF(i, a, b) for(int i = a; i >= b; i--)
#define ms memset
#define pb push_back
#define fi first
#define se second
#define inp(n, a) vector<ll> a;for(int i=0;i<n;i++){ll now;cin>>now;a.pb(now);}
#define all(a) a.begin(),a.end()
#define show(a) for(long long i=0;i<(long long)(a.size()-1);i++)cout<<a[i]<<' ';cout<<a[a.size()-1];
long long binpow(long long a, long long b) {
long long res = 1;
while (b > 0) {
if (b & 1)
res = res * a;
a = a * a;
b >>= 1;
}
return res;
}
ll sum2(ll a, ll l, ll n){return (n*(a+l))/2;}
ll ceil2(ll a, ll b){return (a+b-1)/b;}
ll n,d,m;
vector<pll> a;
bool ok(ll x) {
if(x>m)return true;
ll day=1,ind=0;
while(day<=n){
for(ll i=0;i<x;i++){
if(a[ind].fi>day)break;
if(day-a[ind].fi>d)return false;
ind++;
if(ind==m)return true;
}
day++;
}
return true;
}
ll bs() {
ll x=-1;
for(ll b=20;b>=1;b/=2){
while(!ok(x+b))x+=b;
}
return ++x;
}
void solve() {
cin>>n>>d>>m;
for(int i=0;i<m;i++){
ll now;cin>>now;
a.pb({now,i+1});
}
sort(all(a));
ll ans=bs();
cout<<ans<<'\n';
// continue output the list of schedule
ll day=1,ind=0;
while(day<=n){
for(ll i=0;i<ans;i++){
if(ind==m)break;
if(a[ind].fi>day)break;
cout<<a[ind].se<<' ';
ind++;
}
day++;
cout<<"0\n";
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(NULL);
solve();
}
