#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n, d, m;
cin >> n >> d >> m;
vector<int> a(m);
for (int i = 0; i < m; i++) {
cin >> a[i];
--a[i];
}
vector<int> order(m);
iota(order.begin(), order.end(), 0);
sort(order.begin(), order.end(), [&](int i, int j) {
return a[i] < a[j];
});
vector<vector<int>> days(n);
auto Can = [&](int machines) {
for (int i = 0; i < n; i++) {
days[i].clear();
}
int day = 0;
int emptyMachines = machines;
for (int id = 0; id < m; id++) {
int cur = a[order[id]];
if (cur > day) {
day = cur;
emptyMachines = machines;
} else if (cur + d < day) {
return false;
}
days[day].push_back(order[id]);
if (--emptyMachines == 0) {
day++;
emptyMachines = machines;
}
}
return true;
};
int low = 1, high = 1000000000;
while (low <= high) {
int mid = low + (high - low) / 2;
if (Can(mid)) {
high = mid - 1;
} else {
low = mid + 1;
}
}
Can(high + 1);
cout << high + 1 << '\n';
for (int i = 0; i < n; i++) {
for (int j = 0; j < (int) days[i].size(); j++) {
if (j > 0) {
cout << " ";
}
cout << 1 + days[i][j];
}
if ((int) days[i].size() > 0) {
cout << " ";
}
cout << "0\n";
}
return 0;
}
