//#pragma GCC optomize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("O3")
//#pragma GCC target("avx2")
//#pragma GCC target("sse,sse2,sse4.1,sse4.2")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define max_heap priority_queue<pair <ll, pair <ll, ll>>>
#define min_heap priority_queue<pair <ll, ll>, vector<pair <ll, ll>>, greater<pair <ll, ll>>>
//#define min_heap priority_queue<ll, vector<ll>, greater<ll>>
#define sariE cin.tie(NULL); cout.tie(NULL); ios_base::sync_with_stdio(false);
#define filE freopen("in.txt", "r", stdin); freopen("out1.txt", "w", stdout);
#define endl '\n'
#define md(a) (a % mod + mod) % mod
#define pb push_back
//cout << vectorprecision(5) << fixed << f;
//hash prime = 769
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll const maxn = 2e5 + 123;
ll const inf = 2e18;
ll const loG = 23;
ll const mod = 1e9 + 7;
//ll const mod = 998244353;
ll const sq = 350;
ll power(ll a, ll b, ll mod){if(b==0)return 1;if(b==1)return a;ll x = power(a, b / 2, mod);return (((x * x) % mod) * (b % 2 ? a : 1)) % mod;}
int n, m, d;
vector <int> arr[maxn], ans[maxn];
void Solve(){
cin >> n >> d >> m;
for (int i = 1; i < m + 1; i++){
int x; cin >> x;
arr[x].push_back(i);
}
int l = 0, r = mod;
while (r - l > 1){
int mid = (l + r) / 2;
int roz = 0;
int ja = 0;
bool ok = 1;
for (int i = 1; i < n + 1; i++){
int x = arr[i].size();
if (ja < x){
int y = (x - ja);
if (y % mid == 0)
y = y / mid;
else
y = y / mid + 1;
roz += y;
ja += mid * y;
}
ja -= x;
if (roz - i > d || (roz > n)){
ok = 0;
break;
}
}
if (ok)
r = mid;
else
l = mid;
}
//cout << "ans is " << r << endl;
cout << r << endl;
int ja = 0, roz = 0;
for (int i = 1; i < n + 1; i++){
for (int x : arr[i]){
if (roz < i){
roz = i;
ja = r;
}
if (ja == 0){
roz++;
ja += r;
}
ans[roz].pb(x);
ja--;
}
}
for (int i = 1; i < n + 1; i++){
for (int x : ans[i])
cout << x << ' ';
cout << 0 << endl;
}
}
int main(){
sariE;// filE;
int test = 1;
//cin >> test;
while (test--) Solve();
return 0;
}
