#include <bits/stdc++.h>
const std::string filename = "sabotage";
using namespace std;
#define c() {cout << "CHECKPOINT\n";}
#define b(I) {cout << "BREAKPOINT. POINT: " << I << "\n";}
#define cb(G, I) {if(G) cout << "CONDITIONAL BREAKPOINT. FUFILLS " << #G << ". POINT: " << I << "\n";}
#define see(ARRAY) {cout<<"Watching Values Of "<<#ARRAY<<" { ";for(auto& e : ARRAY) {cout << e << " ";}cout<<" }\n";}
#define see2d(ARRAY) {cout<<"Watching Values Of "<<#ARRAY<<"\n {\n";for(auto&e:ARRAY){cout<<"{ ";for(auto&a:e){cout<<a<<" ";}cout<<"}\n";}cout<<" }\n";}
#define see2dE(ARRAY,A) {cout<<"Watching Values Of "<<#ARRAY<<" with bounds " << A << "\n {\n";for(int i=0; i < A; i++){for(int j = 0; j < A; j++)cout<<ARRAY[i][j]<<" ";cout<<"\n";}cout<<" }\n";}
#define see2dF(ARRAY,A) {cout<<"Watching Values Of "<<#ARRAY<<" with semibounds " << A << "\n {\n";for(int i=0; i < A; i++){for(int j = 0; j < (int)(ARRAY[i].size()); j++)cout<<ARRAY[i][j]<<" ";cout<<"\n";}cout<<" }\n";}
#define seePair(PAIR) {cout<<"Watching Value Of "<<#PAIR<<" { "<<PAIR.first<<", "<<PAIR.second<<" }\n";};
#define mset multiset
#define inv_priority_queue priority_queue<ll, vector<ll>, greater<ll>>
#define ll long long
#define ld long double
#define pi pair<int, int>
#define pd pair<double, double>
#define pl pair<long long, long long>
#define szv(x) ((int)x.size())
#define sza(x) (int)(sizeof(x))
#define vall(a) (a).begin(), (a).end()
#define aall(a) a, a+(int)(sizeof(a))
#define mkp make_pair
#define fr first
#define sc second
#define bk back
#define pb push_back
#define ct cout <<
const int dirs[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
const int MAX_N = 1e5 + 5;
const int MAX_DN = 105;
const ll MOD = 1e9 + 7;
const ll INF = 1e9;
const ld EPS = 1e-9;
vector<pi> A;
pair<bool, vector<vector<int>>> works(ll test, int D) {
vector<vector<int>> schedule;
int i = 0, count = 1, next = test;
while(i < szv(A)) {
schedule.pb({});
if(!(count - A[i].fr <= D)) return mkp(false, schedule);
for( ; i < min(next, szv(A)); i++) {
if(count - A[i].fr < 0) break;
schedule.back().pb(A[i].sc);
}
schedule.back().pb(0);
count++;
next += test;
}
return mkp(true, schedule);
}
void solve(int testcase) {
int N, D, M;
cin >> N >> D >> M;
for(int i = 0; i < M; i++) {
int a;
cin >> a;
A.pb({a, i+1});
}
sort(vall(A));
ll l = 1, h = M;
while(l < h) {
ll mid = (l + h) / 2;
if(works(mid, D).fr) {
h = mid;
} else {
l = mid+1;
}
}
vector<vector<int>> ans = works(l, D).sc;
cout << l << "\n";
for(auto& e : ans) {
for(auto& c : e) {
cout << c << " ";
}
cout << "\n";
}
}
void setIO() { // name is nonempty for USACO file I/O
string name = filename;
ios_base::sync_with_stdio(0); cin.tie(0); // see Fast Input & Output
cin.tie(0)->sync_with_stdio(0);
if (!(name == "*")) {
freopen((name+".in").c_str(), "r", stdin); // see Input & Output
freopen((name+".out").c_str(), "w", stdout);
}
}
int main() {
//ios_base::sync_with_stdio(0);
//cin.tie(0); cout.tie(0);
//setIO();
int tc = 1;
//cin >> tc;
for (int t = 1; t <= tc; t++) {
// cout << "Case #" << t << ": ";
solve(t);
}
}
