#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define indexed_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
typedef long long ll;
using namespace std;
int xor1(int n){ if (n % 4 == 0) return n; if (n % 4 == 1) return 1; if (n % 4 == 2) return n + 1; return 0;}
template <class T> bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; }
template <class T> bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }
ll mod=1e9 + 7;
#define test ll t;cin>>t;while(t--)
#define mp make_pair
#define all(a) a.begin(),a.end()
#define pb push_back
#define re(i,n) for(ll i=0;i<n;i++)
#define reb(i,n) for(ll i=n-1;i>=0;i--)
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<string> vs;
typedef map<ll,int> ml;
typedef map<char,ll> mc;
typedef map<string,ll> ms;
typedef vector<pair<ll,ll>> vpl;
#define fi first
#define se second
using namespace std::chrono;
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll n,d,m; cin>>n>>d>>m;
vpl v(m);
re(i,m){
cin>>v[i].fi;
v[i].se=i+1;
}
sort(all(v));
auto chk=[&](ll x){
ll day=1,cnt=0;
re(i,m){
if(cnt==x){
cnt=0;
day++;
}
cnt++;
if((v[i].fi+d)<(day)){
return 0;
}
}
return 1;
};
// for(auto x:v)cout<<x.fi<<" ";
// cout<<'\n';
ll lo=1,hi=m,ans=0;
while(lo<hi){
ll mid=(lo+hi)/2;
//cout<<mid<<'\n';
if(chk(mid)){
ans=mid;
hi=mid;
}
else lo=mid+1;
}
cout<<ans<<'\n';
int it=0;
re(i,n){
int cnt=0;
while(it<m){
cnt++;
cout<<v[it].se<<" ";
it++;
if(cnt>=ans)break;
}
cout<<"0\n";
}
return 0;
}
