#include <iostream>
#include <vector>
#include <deque>
#include <set>
#include <queue>
#include <string>
#include <limits>
#include <map>
#include <algorithm>
#include <stack>
using namespace std;
using ll = long long int;
const ll mod = 1e9 + 7;
bool possible(vector<pair<int,int>>& v, int d, int m){
priority_queue<pair<int,int>> q;
int day = 1;
for(auto i : v){
q.push({-i.first, i.second});
int sum = 0;
while(!q.empty() && sum < m){
auto p = q.top(); q.pop();
p.first = -p.first;
if(day >= p.first + d){ //!!
return false;
}
if(p.second > m - sum){
q.push({-p.first, p.second - (m - sum)});
}
sum += p.second;
}
++day;
}
return true;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
int n, d, m;
cin >> n >>d >> m;
vector<pair<int,int>> v(m);
for(int i = 0; i < m; ++i){
cin >> v[i].first;
v[i].second = i + 1;
}
sort(begin(v), end(v));
vector<pair<int,int>> compressed;
for(int i = 0; i < m; ++i){
if(compressed.empty() || compressed.back().first != v[i].first){
compressed.push_back(make_pair(v[i].first, 0));
}
++compressed.back().second;
}
int l = 1, r = m;
while(l < r){
int middle = (l + r) / 2;
if(possible(compressed, d, middle)){
r = middle;
}
else{
l = middle + 1;
}
}
cout << l << endl;
int i = 0;
int day = 1;
while(i < m){
int ctr = 1;
cout << v[i].second << " ";
++i;
while(i < m && ctr < l && v[i].first <= day){
cout << v[i].second << " ";
++ctr;
++i;
}
++day;
cout << 0 << "\n";
}
while(day <= n){
cout << 0 << "\n";
++day;
}
}
