#include "bits/stdc++.h"
#ifdef LOCAL
#include "bits/debug.h"
#else
#define dd(...) 42
#endif
#define ll long long
#define ull unsigned long long
#define nl '\n'
#define all(a) begin(a), end(a)
#define rall(a) rbegin(a) rend(a)
#define sz(a) ((int)a.size())
#define ff first
#define ss second
#define f(i, n) for (int i = 0; i < n; ++i)
// #define PROB_NAME "sliding"
using namespace std;
// const int INF = 1e9;
// const ll INFF = 1e18;
// const int M = 1e9 + 7;
ll d, h, n, m, k, p, q, x, y, z;
bool pos(ll cnt[], ll M) {
ll dlay = 0;
f(i, n) { dlay = max(cnt[i] / M, dlay); }
return dlay <= d;
}
void solve() {
cin >> n >> d >> m;
ll a[m];
f(i, m) cin >> a[i];
ll cnt[n];
f(i, n) cnt[i] = 0;
f(i, m) cnt[a[i]]++;
ll L = 1;
ll R = 1e9;
ll ans = R;
while (L <= R) {
ll M = L + (R - L) / 2;
if (pos(cnt, M)) {
ans = min(ans, M);
R = M - 1;
} else {
L = M + 1;
}
}
cout << ans << nl;
vector<pair<ll, ll>> A;
f(i, m) A.push_back({a[i], i + 1});
sort(all(A));
map<ll, vector<ll>> M;
// f(i, n) cerr << cnt[i] << " ";
ll i = 0;
ll day = 1;
while (i < m && day <= n) {
while (i < m && sz(M[day]) < ans) {
M[day].push_back(A[i].ss);
++i;
}
++day;
}
ll pr = 0;
for (auto& e : M) {
f(ii, sz(e.ss)) cout << e.ss[ii] << ' ';
cout << '0' << nl;
++pr;
}
while (pr < n) {
cout << 0 << nl;
++pr;
}
}
void TESTCASES() {
int t = 1;
// cin >> t;
for (int i = 1; i <= t; ++i) {
solve();
}
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
#ifdef PROB_NAME
freopen(PROB_NAME ".in", "r", stdin);
freopen(PROB_NAME ".out", "w", stdout);
#endif
TESTCASES();
}
