#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("Ofast,unroll-loops")
using namespace std;
using namespace __gnu_pbds;
#define pb push_back
#define all(x) x.begin(),x.end()
#define int long long
#define ar array
#define mrand(a, b) uniform_int_distribution<int>(a, b)(rng)
template<class T>bool umax(T &a,T b){if(a<b){a=b;return true;}return false;}
template<class T>bool umin(T &a,T b){if(b<a){a=b;return true;}return false;}
template<class T> using ste = tree<T, null_type, less_equal<T>,
rb_tree_tag, tree_order_statistics_node_update>;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
namespace FAST {
template<typename T, typename F>
istream &operator>>(istream &cin, pair<T, F> &p) {
cin >> p.first >> p.second;
return cin;
}
template<typename T, typename F>
ostream &operator<<(ostream &cout, pair<T, F> &p) {
cout << p.first << ' ' << p.second;
return cout;
}
template<typename T>
istream &operator>>(istream &cin, vector<T> &a) {
for (T &i: a) cin >> i;
return cin;
}
template<typename T>
ostream &operator<<(ostream &cout, vector<T> &a) {
for (T i: a) cout << i << ' ';
return cout;
}
template<typename T>
istream &operator>>(istream &cin, deque<T> &a) {
for (T &i: a) cin >> i;
return cin;
}
template<typename T>
ostream &operator<<(ostream &cout, deque<T> &a) {
for (T i: a) cout << i << ' ';
return cout;
}
}
using namespace FAST;
const int inf = 1e17 + 7;
const int mod = 1e9 + 7;
const int N = 1e6 + 5;
const int md = 998244353;
int binpow(int a, int b, int m){
if(b == 0)return 1;
if(b % 2 == 0){
int c = binpow(a,b/2,m);
return (c*c)%m;
}
return (binpow(a,b-1,m)*a)%m;
}
int divi(int a, int b, int m){
return (a*(binpow(b,m-2, m)))%m;
}
struct Bit {
vector<int> b, b2;
int n;
Bit(int n) {
this->n = n + 1;
b.assign(n + 1, 0);
b2.assign(n+1, 0);
}
void add(vector<int>&b, int idx, int x){
while(idx <= n){
b[idx] += x;
idx += idx & -idx;
}
}
void update(int l, int r, int x){
add(b, l, x);
add(b, r+1, -x);
add(b2, l, x*(l-1));
add(b2, r+1, -x*r);
}
int sum(vector<int>&b, int idx){
int res = 0;
while(idx > 0){
res += b[idx];
idx -= idx & -idx;
}
return res;
}
int pref(int idx){
return sum(b, idx) * idx - sum(b2, idx);
}
int get(int l, int r){
return pref(r) - pref(l-1);
}
};
int n,m,k;
void solve(){
cin >> n >> m >> k;
vector<int>g[n+5];
for(int i = 0;i<k;i++){
int a;
cin >> a;
g[a].pb(i + 1);
}
int l = 1, r = k, ans = -1;
while(l <= r){
int mid = (l + r) / 2;
bool flag = true;
queue<ar<int,2>>q;
for(int i = 1;i<=n;i++){
for(auto to:g[i])q.push({i, to});
// cout << i << "\n";
// for(auto to:g[i])cout << to << " ";
// cout << "\n";
if(!q.empty() && q.front()[0] + m < i){
flag = false;
break;
}
// if(mid == 3)
// cout << q.size() << "\n";
int b = mid;
while(!q.empty() && b > 0){
b -= 1;
q.pop();
}
// if(mid == k)
}
if(flag){
r = mid - 1;
ans = mid;
}
else l = mid + 1;
}
cout << ans << "\n";
queue<ar<int,2>>q;
for(int i = 1;i<=n;i++){
for(auto to:g[i])q.push({i, to});
int b = ans;
while(!q.empty() && b > 0){
cout << q.front()[1] << " ";
b -= 1;
q.pop();
}
cout << 0 << "\n";
}
}
/*
*/
signed main()
{
// freopen("seq.in", "r", stdin);
// freopen("seq.out", "w", stdout);
ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);
int tt=1;// cin >> tt;
while(tt--)solve();
}
