#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define mp make_pair
using namespace std;
const int maxn = 100100;
int n, d, m, x;
int arr[maxn];
vector<int>v[maxn];
vector<int>result[maxn];
bool check(int x) {
deque<pair<int,int> > dq;
for(int i=1;i<=n;i++) {
dq.pb(mp(i, arr[i]));
int value = x;
while(value > 0 && dq.size()) {
if(dq.front().first < i - d) return false;
if(dq.front().second <= value) {
value -= dq.front().second;
dq.front().second = 0;
}
else {
dq.front().second -= value;
value = 0;
}
if(dq.front().second == 0) dq.pop_front();
}
while(dq.front().second == 0 && dq.size()) dq.pop_front();
}
return dq.size() == 0;
}
void get_result(int x) {
deque<pair<int,int> > dq;
for(int i=1;i<=n;i++) {
dq.pb(mp(i, arr[i]));
int value = x;
while(value > 0 && dq.size()) {
if(dq.front().second <= value) {
value -= dq.front().second;
for(int j=0;j<dq.front().second;j++) {
result[i].pb(v[dq.front().first].back());
v[dq.front().first].pop_back();
}
dq.front().second = 0;
}
else {
dq.front().second -= value;
for(int j=0;j<value;j++) {
result[i].pb(v[dq.front().first].back());
v[dq.front().first].pop_back();
}
value = 0;
}
if(dq.front().second == 0) dq.pop_front();
}
}
for(int i=1;i<=n;i++) {
for(int j:result[i]) cout<<j<<" ";
cout<<"0\n";
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin>>n>>d>>m;
for(int i=1;i<=m;i++) {
cin>>x;
arr[x]++;
v[x].pb(i);
}
int maxv = 0;
for(int i=1;i<=n;i++) {
maxv = max(maxv, arr[i]);
}
int li = 1, ri = m;
while(li < ri) {
int mid = (li+ri)/2;
if(check(mid)) ri = mid;
else li = mid + 1;
}
cout<<li<<"\n";
get_result(li);
return 0;
}
