#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector <int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vs = vector <string>;
using vb = vector <bool>;
using vd = vector <double>;
using vc = vector <char>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vpii = vector <pii>;
int n, d, m;
vpii quests;
bool binarySearch(ll mid, vector<vi> &days){
int cnt = 0;
int last = 1;
for(int i = 0; i < m and last <= n; i++){
if(quests[i].first + d < last)
return false;
if(quests[i].first < last){
i--;
last++;
cnt = 0;
continue;
}
if(cnt + 1 > mid)
{
last++;
cnt = 0;
if(last == n)
break;
}
days[last - 1].push_back(quests[i].second);
cnt++;
}
if(last == n)
return false;
return true;
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cin>>n>>d>>m;
quests = vpii(m);
for(auto &x : quests)
cin>>x.first;
for(int i = 0; i < m; i++){
quests[i].second = i + 1;
}
sort(quests.begin(), quests.end());
int l = 1, r = m + 1;
r = 4;
vvi ans;
while(l + 1 < r){
ll mid = (l + r) / 2;
vector<vi> days(n);
if(binarySearch(mid, days)){
r = mid;
ans = days;
}
else{
l = mid;
}
}
cout<<r<<'\n';
for(int i = 0; i < ans.size(); i++){
for(auto x : ans[i]){
cout<<x<<" ";
}
cout<<"0\n";
}
}
