#include <bits/stdc++.h>
using namespace std;
bool ok(int machines, vector<pair<int, int>>& t, int m, int d, int n) {
int i = 0;
for (int day = 1; day <= n-d; day++) {
int j = i;
for (; j < i+machines && j < m; j++) {
if (day < t[j].first) {
break;
}
}
i = j;
if (i == m) {
return true;
}
}
return false;
}
int main() {
int n, d, m;
cin >> n >> d >> m;
vector<pair<int, int>> t(m);
for (int i = 0; i < m; i++) {
cin >> t[i].first;
t[i].second = i+1;
}
sort(t.begin(), t.end());
int lo = 1;
int hi = m;
while (lo < hi) {
int mid = (lo+hi)/2;
if (ok(mid, t, m, d, n)) {
hi = mid;
} else {
lo = mid+1;
}
}
cout << lo << endl;
int lines = 0;
for (int i = 0; i < m; i++) {
cout << t[i].second << " ";
if (i%lo == lo-1) {
cout << 0 << endl;
lines++;
}
}
for (int i = lines; i < n; i++) {
cout << 0 << endl;
}
return 0;
}
