#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 day = 1;
ll w = 0;
while(w<m){
if(day>n){
return false;
}
for(ll i = 0; i < dd; i++){
if(w>m){
break;
}
if(v[w].first+d<day){
return false;
}
w++;
}
day++;
}
return true;
}
int main(){
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;
reverse(v.begin(), v.end());
cout << l << "\n";
while(!v.empty()){
counter++;
for(ll i = 0; i < l; i++){
cout << v.back().second+1 << " ";
v.pop_back();
if(v.empty()){
break;
}
}
cout << "0\n";
}
for(ll i = 0; i < n-counter; i++){
cout << 0 << "\n";
}
}
