#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
#include <array>
//#include <ext/pb_ds/tree_policy.hpp>
//#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
//using namespace __gnu_pbds;
#define FOR(i,start,end) for(int i=start;i<(int)(end);i++)
#define FORE(i,start,end) for(int i=start;i<=(int)end;i++)
#define RFOR(i,start,end) for(int i = start; i>end; i--)
#define RFORE(i,start,end) for(int i = start; i>=end; i--)
#define all(a) a.begin(), a.end()
#define mt make_tuple
#define mp make_pair
#define v vector
#define sf scanf
#define pf printf
#define dvar(x) cout << #x << " := " << x << "\n"
#define darr(x,n) FOR(i,0,n) cout << #x << "[" << i << "]" << " := " << x[i] << "\n"
typedef long long ll;
typedef long double ld;
typedef pair<int, int > pii;
typedef pair<ll, ll> pll;
//template <class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<class T> void minn(T &a, T b) { a = min(a, b); }
template<class T> void maxx(T &a, T b) { a = max(a, b); }
void io() {
#ifdef LOCAL_PROJECT
freopen("input.in", "r", stdin); freopen("output.out", "w", stdout);
#else
#endif
ios_base::sync_with_stdio(false); cin.tie(NULL);
}
const ll INF = 1e14;
/***************************ceoi2012_Day1_jobs.cpp*******************************/
int N, D, M;
v<int> jobs[100000];
bool isPossible(int mach) {
queue<int> q; // <time>
FOR(i, 0, N) {
for (auto j : jobs[i]) q.push(i);
int reps = min(mach, (int)q.size());
FOR(x, 0, reps) {
int cur = q.front();
q.pop();
if (i > D + cur)
return 0;
}
}
return q.empty();
}
void print(int mach) {
cout << mach << "\n";
queue<int> q; // <id>
FOR(i, 0, N) {
for (auto j : jobs[i]) q.push(j);
int reps = min(mach, (int)q.size());
FOR(x, 0, reps) {
int cur = q.front();
cout << cur << " ";
q.pop();
}
cout << "0\n";
}
}
int main() {
io();
cin >> N >> D >> M;
FORE(i, 1, M) {
int day; cin >> day;
jobs[day - 1].push_back(i);
}
int lo = 1, hi = M;
while (lo < hi) {
int mi = (lo + hi) / 2;
if (isPossible(mi) == false) lo = mi + 1;
else hi = mi;
}
print(lo);
}
