#include <algorithm>
#include <iostream>
using namespace std;
string ans;
long long N, D, M, a;
const long long max_m = 1e6;
pair<int, int> job_requests[max_m];
bool check(long long m) {
string t = "";
long long day = 0;
long long job_index = 0;
bool stop = false;
while (job_index < M && day < (N + D)) {
day++;
for (int i = 0; i < m; i++) {
long long c_day = job_requests[job_index].first;
if (day > c_day + D) {stop = true; break; }
t.append(to_string(job_requests[job_index].second + 1));
t.append(" ");
job_index++;
}
t.append("0\n");
if (stop) break;
}
for (long long i = day; i < N; i++) {
t.append("0\n");
}
if (job_index == M) ans = t;
return job_index == M;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> N >> D >> M;
for (int i = 0; i < M; i++) {
cin >> a;
job_requests[i] = make_pair(a, i);
}
sort(job_requests, job_requests + M);
long long l = 0, r = M;
while (l < r) {
long long m = l + (r - l) / 2;
if (check(m)) {
r = m;
} else {
l = m + 1;
}
}
cout << r << "\n" << ans << "\n";
return 0;
}
