#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
std::mt19937 rng(std::chrono::steady_clock::now().time_since_epoch().count());
const ll MOD = 1e9 + 7;
const ll INF = 1e9 + 7;
bool bipartite;
const int MAXN = 200005;
ll fact[MAXN];
ll h, c, t;
const ll NEG_INF = -1e17 - 7;
vector<vector<int>> f(int machine_cnt, vector<pair<int,int>> &arrivals, int d, int n){
int m = arrivals.size();
vector<vector<int>>schedule(n+1);
int ptr = 0;
for(int i=1;i<=n;i++){
int cur_day_machine_used = 0;
while(cur_day_machine_used < machine_cnt){
if(ptr >= m) return schedule;
if(arrivals[ptr].first > i){
//it means cur job ka arrival cur day se baad ka hai
cur_day_machine_used = 0;
break;
}
if(arrivals[ptr].first + d < i){
return {};
}
cur_day_machine_used++;
schedule[i].push_back(arrivals[ptr].second);
ptr++;
if(ptr == m) return schedule;
}
}
return {};
}
void solve()
{
int n, m, d;
cin>>n>>d>>m;
vector<int>jobs(m);
vector<pair<int,int>>arrivals(m);
for(int i=0;i<m;i++){
cin>>jobs[i];
arrivals[i] = {jobs[i], i+1};
}
sort(arrivals.begin(), arrivals.end());
vector<vector<int>> res;
int low = 0, high = m+1, ans = 0;
while(low <= high){
int mid = (low + high)/2;
vector<vector<int>>temp = f(mid, arrivals, d, n);
if(!temp.empty()){
ans = mid;
res = temp;
high = mid - 1;
}
else{
low = mid + 1;
}
}
cout<<ans<<endl;
for(int i=1;i<=n;i++){
for(auto it: res[i]){
cout<<it<<" ";
}
cout<<0<<endl;
}
return;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t;
t = 1;
while (t--)
{
solve();
}
return 0;
}
