#include <bits/stdc++.h>
using namespace std;
using ll = long long;
ll n,d,m;
vector<pair<ll,ll>> v;
bool ok(ll dd){
ll c = 0; ll day = 1;
for(int i = 0; i < m; i++){
if(day>n){
return false;
}
if(day>v[i].first+d){
return false;
}
if(day<v[i].first){
c=0;
day=v[i].first;
}
c++;
if(c==dd){
day++;
c=0;
}
}
return true;
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> d >> m;
for(ll i = 0; i < m; i++){
ll x; cin >> x;
v.push_back({x,i});
}
sort(v.begin(), v.end());
ll l = 1,r=m;
while(l<r){
ll mid = (l+r)/2;
if(ok(mid)){
r=mid;
}
else{
l=mid+1;
}
}
ll counter=0;
ll cur = 0;
cout << l << "\n";
while(cur<m){
counter++;
for(ll i = 0; i < l; i++){
cout << v[cur].second+1 << " ";
cur++;
if(cur==m){
break;
}
}
cout << "0\n";
}
for(ll i = 0; i < n-counter; i++){
cout << 0 << "\n";
}
}
