#include <bits/stdc++.h>
using namespace std;
int main() {
int n, d, m;
cin >> n >> d >> m;
vector<pair<int, int>> a(m);
for (int i = 0; i < m; i++) {
cin >> a[i].first;
a[i].second = i;
}
sort(a.begin(), a.end());
vector<vector<int>> ans;
int lo = 1, hi = m;
while (lo < hi) {
int mid = (lo+hi)/2;
int day = 1;
vector<vector<int>> v(n+1);
int cnt = 0;
for (int i = 0; i < m; i++) {
if (cnt == mid) {
day++;
cnt = 0;
}
if (a[i].first > day) {
day = a[i].first;
cnt = 0;
}
else if (day > a[i].first+d) {
v.clear();
break;
}
v[day].push_back(a[i].second+1);
cnt++;
}
if (!v.empty()) {
hi = mid;
ans = v;
}
else lo = mid+1;
}
cout << hi << '\n';
for (int i = 1; i <= n; i++) {
for (auto x : ans[i]) cout << x << ' ';
cout << "0\n";
}
return 0;
}
