#include "bits/stdc++.h"
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
using i32 = int;
using u32 = unsigned;
using i16 = short;
using u16 = unsigned short;
using ld = long double;
using ii = pair<int, int>;
void solve() {
int n, d, m;
cin >> n >> d >> m;
vector<ii> job(m);
for(int i = 0; i < m; ++i) {
cin >> job[i].first;
job[i].second = i + 1;
}
sort(job.begin(), job.end());
int lo = 1, hi = m;
while(lo < hi) {
int mid = (lo + hi) / 2, j = 0;
bool ok = true;
for(int i = 1; i <= n && j < m; ++i) {
int k = j;
while(k < m && k - j < mid && job[k].first <= i) {
ok = ok && i - job[k].first <= d;
++k;
}
j = k;
}
if(ok && j == m) hi = mid;
else lo = mid + 1;
}
cout << hi << '\n';
vector<vector<int>> sch(n + 1);
for(int i = 1, j = 0; i <= n; ++i) {
int k = j;
while(k < m && k - j < hi && job[k].first <= i) sch[i].push_back(job[k++].second);
j = k;
}
for(int i = 1; i <= n; ++i) {
for(int id : sch[i]) cout << id << ' ';
cout << "0\n";
}
}
int main() {
ios_base :: sync_with_stdio(false);
cin.tie(0);
int t = 1;
//cin >> t;
while(t--) solve();
return 0;
}
