#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma")
#include <bits/stdc++.h>
using num = int64_t;
using namespace std;
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define REPI(t, n) for (num t = 0; t < n; ++t)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
#ifdef TESTING
#define DEBUG(...) __VA_ARGS__
#else
#define DEBUG(...)
#endif
bool possible(vector<vector<num>> &jobs, num D, num M) {
num N = sz(jobs);
vector<num> jobsLeft(N);
num idx = 0;
REPI(i, N) {
if (idx+D < i) return false;
jobsLeft[i] = sz(jobs[i]);
num spent = 0;
while (spent < M) {
if (idx > i) break;
num canSpend = min(M-spent, jobsLeft[idx]);
jobsLeft[idx] -= canSpend;
spent += canSpend;
if (jobsLeft[idx] == 0) ++idx;
}
}
while ((idx < N) && (jobsLeft[idx] == 0)) ++idx;
return (idx == N);
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit);
num N, D, M;
cin >> N >> D >> M;
vector<vector<num>> jobs(N);
REPI(i, M) {
num x;
cin >> x;
--x;
jobs[x].push_back(i+1);
}
num lo = 1, hi = M;
while (lo < hi) {
num mid = (lo+hi) >> 1;
if (possible(jobs, D, mid)) hi = mid;
else lo = mid+1;
}
queue<num> jobsPending;
vector<vector<num>> ans(N);
REPI(i, N) {
for (num job : jobs[i]) jobsPending.push(job);
REPI(j, lo) {
if (jobsPending.empty()) break;
num curJob = jobsPending.front();
jobsPending.pop();
ans[i].push_back(curJob);
}
}
cout << lo << "\n";
REPI(i, N) {
for (num job : ans[i]) cout << job << " ";
cout << "0\n";
}
}
