#include<iostream>
#include<algorithm>
using namespace std;
int n, d, m; // available days, max delay, job count
pair<int, int> arrive[1000001]; // when the jobs come in
bool isok(int machines) {
int current = 0;
for (int i = 1; i <= n; i++) {
int machines_left = machines;
while (machines_left > 0 && current < m && arrive[current].first <= i) {
if (i - arrive[current].first >= d) {
return false;
}
machines_left--;
current++;
}
}
return current == m; // can complete all jobs
}
int main() {
cin >> n >> d >> m;
for (int i = 0; i < m; i++) {
cin >> arrive[i].first;
arrive[i].second = i + 1;
}
sort(arrive, arrive + m);
int left = 1, right = m;
int ans = 1;
while (left <= right) {
int mid = (left + right) / 2; // bsearch for how many machines needed
if (isok(mid)) {
ans = mid;
right = mid - 1;
} else {
left = mid + 1;
}
}
cout << ans << endl;
int current = 0;
for (int i = 1; i <= n; i++) {
int machines_left = ans;
while (machines_left > 0 && current < m && arrive[current].first <= i) {
cout << arrive[current].second << " ";
machines_left--;
current++;
}
cout << 0 << endl;
}
}
