#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef pair<int,int> pii;
typedef pair<int64,int> pii32;
typedef pair<int64,int64> pii64;
#define PB push_back
#define MP make_pair
#define F first
#define S second
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
const int maxn = 1e5+10;
const int64 MO = 1e9+7;
const int64 IN = 1e9;
queue <pii> q1;
vector <int> v1[maxn];
int n, d, m;
int main () {
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> d >> m;
for (int i = 0; i < m; i++) {
int x;
cin >> x;
v1[x].PB(i + 1);
}
int l, r, mid;
l = 0;
r = m;
while (r - l > 1) {
mid = (l + r) >> 1;
while(sz(q1)) q1.pop();
bool ok = 1;
for (int i = 1; i <= n; i++) {
if (sz(q1) && q1.front().F < i - d)
ok = 0;
for (auto x : v1[i])
q1.push(MP(i, x));
for (int t = 0; t < mid && sz(q1); t++)
q1.pop();
}
if (sz(q1))
ok = 0;
if (ok)
r = mid;
else
l = mid;
}
cout << r << "\n";
while(sz(q1)) q1.pop();
for (int i = 1; i <= n; i++) {
for (auto x : v1[i])
q1.push(MP(i, x));
for (int t = 0; t < r && sz(q1); t++) {
cout << q1.front().S << " ";
q1.pop();
}
cout << "0\n";
}
}
