#include <iostream>
#include <set>
using namespace std;
int n,d,m,val;
multiset<int> requests;
multiset<pair<int,int>> identifiers;
bool solve(int crtd) {
multiset<int> req = requests,todo;
for (int i = 1;i<=n;++i) {
while(!req.empty()&&*req.begin()<=i) {
todo.insert(*req.begin());
req.erase(req.find(*req.begin()));
}
for (int j = 1;j<=crtd;++j) {
if (!todo.empty()) {
int num = *todo.begin();
todo.erase(todo.find(*todo.begin()));
if (num+d<i) {
return 0;
}
}
}
}
if (!todo.empty())
return 0;
return 1;
}
int main() {
cin>>n>>d>>m;
for (int i = 1;i<=m;++i) {
cin>>val;
requests.insert(val);
identifiers.insert({val,i});
}
int st = 1,dr = n;
while(st<dr) {
int mid = (st+dr)/2;
if (solve(mid)) {
dr = mid;
} else {
st = mid+1;
}
}
cout<<dr<<'\n';
int crtd = dr;
multiset<pair<int,int>> todo;
// modify RED
for (int i = 1;i<=n;++i) {
while(!identifiers.empty()&&(*identifiers.begin()).first<=i) {
todo.insert(*identifiers.begin());
identifiers.erase(identifiers.find(*identifiers.begin()));
}
for (int j = 1;j<=crtd;++j) {
if (!todo.empty()) {
auto el = *todo.begin();
int num = el.first;
cout<<el.second<<" ";
todo.erase(todo.find(*todo.begin()));
}
}
cout<<0<<'\n';
}
if (!todo.empty())
return 0;
return 0;
}
