#include <bits/stdc++.h>
using namespace std;
#define vi vector<int>
#define ii pair<int, int>
#define vii vector<ii>
#define vll vector<long long>
constexpr int MOD = 1'000'000'007;
#define endl '\n'
#define FAST ios_base::sync_with_stdio(false), cin.tie(nullptr);
#define ALL(x) begin(x), end(x)
#define ll long long
#define ull unsigned long long
#define lld long double
template <typename T = int>
istream &operator>>(istream &in, vector<T> &v) {
for (auto &x : v) in >> x;
return in;
}
template <typename T = int>
ostream &operator<<(ostream &out, const vector<T> &v) {
for (const T &x : v) out << x << ' ';
return out;
}
inline int add(int a, int b) { return a + b >= MOD ? a + b - MOD : a + b; }
inline void inc(int& a, int b) { a = add(a, b); }
inline int sub(int a, int b) { return a - b < 0 ? a - b + MOD : a - b; }
inline void dec(int& a, int b) { a = sub(a, b); }
#ifdef LOCAL
#define debug(x) cerr << #x <<" "; _print(x); cerr << endl;
#else
#define debug(x)
#endif
void solve() {
int n, d, m; cin >> n >> d >> m;
vii jobs(m);
for (int i = 1; i <= m; i++){
jobs[i].second = i;
cin >> jobs[i].first;
}
int l = 1, r = m;
int ans = m;
sort(ALL(jobs));
vector<vi> dist(n);
auto ok = [&](int mid){
multiset<int> availableTimes;
for (int i = 0; i < n; i++){
dist[i].clear();
}
for (int i = 0; i < mid; i++){
availableTimes.insert(0);
}
for (auto ti : jobs){
auto it = availableTimes.begin();
if (*it + 1 > ti.first + d || *it + 1 >= n){
return false;
}
availableTimes.insert(max(ti.first + 1, *it + 1));
dist[max(ti.first, *it)].push_back(ti.second);
availableTimes.extract(*it);
}
return true;
};
while(l <= r){
int mid = (l + r) / 2;
if (ok(mid)){
ans = mid;
r = mid - 1;
} else {
l = mid + 1;
}
}
cout << ans << endl;
for (int i =0; i < n; i++){
for (int j = 0; j < dist[i].size(); j++){
cout << dist[i][j] + 1 << ' ';
}
cout << "0\n";
}
}
int main() {
FAST
int tt=1;
while (tt --> 0) {
solve();
}
}
