#include<bits/stdc++.h>
#include<vector>
using namespace std;
int ar[100004];
int tempar[100004];
int n,d,m;
vector<int> days[100004];
bool check(int mac);
void out(int ans);
int main(){
cin>>n>>d>>m;
int l,r,temp,mid;
for (int i=1;i<=m;i++){
cin>>temp;
ar[temp+d]++;
days[temp+d].push_back(i);
}
l=1;
r=m;
while (l<=r){
mid=(l+r)/2;
if (check(mid)){
r=mid-1;
}
else{
l=mid+1;
}
}
cout<<l<<endl;
out(l);
return 0;
}
bool check(int mac){
for(int i = 1; i <= n; i++) {
tempar[i] = ar[i];
}
int macleft;
int cur=1;
for (int i=1;i<=n;i++){
macleft=mac;
while (macleft>0 && cur<=n){
if (tempar[cur]>0){
tempar[cur]--;
macleft--;
}
else{
cur++;
}
}
if (tempar[i]!=0){
return 0;
}
}
return 1;
}
void out(int ans){
int macleft;
int cur=1;
int temp;
for (int i=1;i<=n;i++){
macleft=ans;
while (macleft>0 && cur<=n){
if (ar[cur]>0){
temp=days[cur][days[cur].size()-1];
days[cur].pop_back();
cout<<temp<<" ";
ar[cur]--;
macleft--;
}
else{
cur++;
}
}
cout<<0<<endl;
}
}
