# include <bits/stdc++.h>
using namespace std;
struct Job{
int index, day, deadline;
};
vector<Job> a;
int n, d, m;
bool cmp(Job a, Job b){
return a.deadline < b.deadline;
}
int main(){
cin >> n >> d >> m;
a.resize(m + 1);
for(int i = 1; i <= m; i++){
Job j;
j.index = i;
cin >> j.day;
j.deadline = j.day + d;
a[i] = j;
}
sort(a.begin(), a.end(), cmp);
int L = 1, R = m;
int res = 0;
vector<vector<int>> resv;
while(L <= R){
int mid = L + (R - L) / 2;
int finished = 0;
bool valid = true;
vector<vector<int>> out(n + 1);
for(int i = 1, j = 1; i <= n; i++){
int machines = mid;
while(j <= m && i >= a[j].day && machines > 0){
if(i > a[j].deadline){
valid = false;
break;
}
out[i].push_back(a[j].index);
machines--;
j++;
finished++;
}
if(!valid) break;
}
if(finished == m){
R = mid - 1;
res = mid;
resv = out;
}
else{
L = mid + 1;
}
}
cout << res << "\n";
for(int i = 1; i <= n; i++){
for(int j = 0; j < (int)resv[i].size(); j++){
cout << resv[i][j] << " ";
}
cout << 0 << "\n";
}
return 0;
}
