#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
using ll = long long;
using ull = unsigned ll;
template<typename T> using vt = vector<T>;
using vi = vt<int>;
using vvi = vt<vi>;
using ii = pair<int, int>;
using vii = vt<ii>;
using indexed_set = tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>;
struct chash {
static ull hash_f(ull x) {x += 0x9e3779b97f4a7c15; x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9; x = (x ^ (x >> 27)) * 0x94d049bb133111eb; return x ^ (x >> 31);}
size_t operator()(ull x) const {static const ull RANDOM = chrono::steady_clock::now().time_since_epoch().count();return hash_f(x + RANDOM);}
};
struct iihash {
template <class T1, class T2>
size_t operator () (const pair<T1,T2> &p) const {auto h1 = hash<T1>{}(p.first);auto h2 = hash<T2>{}(p.second);return h1 ^ h2;}
};
template<class T1, class T2, class T3> using ii_umap = gp_hash_table<pair<T1,T2>,T3,iihash>;
template<class T1, class T2> using f_umap = gp_hash_table<T1,T2,chash>;
template<class T1, class T2> using o_umap = gp_hash_table<T1,T2>;
#define sqr(x) (x)*(x)
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()
#define debug(x) cerr << #x << " -> " << x << '\n'
#define F first
#define S second
#define mp make_pair
#define pb push_back
#define eb emplace_back
const int inf = 1e9 + 7;
const ll infll = 1e18 + 10;
template <typename T> inline T fgcd(T a, T b) {while(b) swap(b, a %= b); return a;}
ll fpow(ll a, ll b) {ll o = 1; for(;b;b >>= 1) {if(b & 1) o = o * a;a = a * a;} return o;}
ll fpow(ll a, ll b, ll m) {ll o = 1; a %= m; for(;b;b >>= 1) {if(b & 1) o = o * a % m;a = a * a % m;} return o;}
template<class T> void uniq(vt<T> &a) {sort(all(a));a.resize(unique(all(a)) - a.begin());}
void setIO(string name = "", string inp = "inp", string out = "out") {
cin.tie(0)->sync_with_stdio(0);
if(sz(name)) {
if(sz(inp)) freopen((name+"."+inp).c_str(), "r", stdin);
if(sz(out)) freopen((name+"."+out).c_str(), "w", stdout);
}
}
int n,d,m,ans;
int main() {
setIO();
cin >> n >> d >> m;
vii a(m);
vi e;
for(int i = 0; i < m; i++) {
cin >> a[i].F;
a[i].S = i + 1;
}
sort(all(a));
int l = 1, r = m;
while(l <= r) {
int mid = (l + r) / 2,cnt = 0;
e.assign(m, 0);
for(int i = 0; i < mid; i++) e[i] = a[i].F;
for(int i = mid; i < m; i++) {
e[i] = max(e[i - mid] + 1, a[i].F);
cnt = max(cnt, e[i] - a[i].F);
}
if(cnt > d) l = mid + 1;
else {
ans = mid;
r = mid - 1;
}
}
e.assign(m, 0);
vvi p(n + 1);
for(int i = 0; i < ans; i++) {
e[i] = a[i].F;
p[e[i]].pb(a[i].S);
}
for(int i = ans; i < m; i++) {
e[i] = max(e[i - ans] + 1, a[i].F);
p[e[i]].pb(a[i].S);
}
cout << ans << '\n';
for(int i = 1; i <= n; i++) {
for(int j : p[i]) cout << j << ' ';
cout << "0\n";
}
return 0;
}
