#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;
for (int day = 1; day <= N; day++) {
long long c_m = 0;
while (c_m < m && job_index < M && job_requests[job_index].first <= day) {
if (job_requests[job_index].first + D >= day) {
t.append(to_string(job_requests[job_index].second + 1));
t.append(" ");
c_m++;
job_index++;
} else return false;
}
t.append("0\n");
}
if (job_index == M) ans = t;
return job_index == M;
// change: cannot work after day M therefore for loop for days and within a for loop for machines?
// 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) return false;
// t.append(to_string(job_requests[job_index].second + 1));
// t.append(" ");
// job_index++;
// }
// t.append("0\n");
// }
//
// 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;
}
/*
Test Case 1:
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
Test Case 2:
1 1 6
1 1 1 1 1 1
Test Case 3:
2 1 6
1 1 1 1 1 1
*/
