#include <bits/stdc++.h>
using namespace std;
#define FOR(a, b) for(ll i = a; i < b; i++)
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL);
typedef long long int ll;
typedef pair<ll, ll> pll; // comments that are mixed
typedef vector<ll> vll; // in with code are placed
typedef vector<pll> vpll; // on the right side
typedef vector<bool> vb;
typedef vector<char> vc;
ll n,d,m;
vector<vll> requests;
bool f(ll machines) {
ll cur_day=1, mach_used=0;
FOR(1, n + 1) {
if(i > cur_day) {
cur_day=i;
mach_used=0;
}
if(!requests[i].size()) continue;
ll amt_days=ceil(requests[i].size() * 1.0f / machines) - 1;
mach_used += requests[i].size() - amt_days * machines;
if(mach_used > machines) {
mach_used -= machines;
amt_days++;
}
cur_day += amt_days;
// cout << i << ": "<< cur_day << " " << mach_used << endl;
if(cur_day - i > d || cur_day > n) return false;
}
return true;
}
int main() {
fast
cin >> n >> d >> m;
requests.resize(n + 1);
FOR(1, m+1) {
ll req;
cin >> req;
requests[req].push_back(i);
}
ll lb=1, upb=m;
while(lb < upb) {
ll mid=(upb + lb)/2;
// cout << "mid :" << mid << endl;
if(f(mid)) upb=mid;
else lb=mid+1;
}
cout << upb << endl;
ll left=upb, cur_day=1;
FOR(1, n+1) {
while(i > cur_day) {
left=upb;
cur_day++;
cout << 0 << endl;
// cout << 1 << " " << cur_day << endl;
}
for(auto x : requests[i]) {
cout << x << " ";
left--;
if(!left) {
cur_day++;
left=upb;
cout << 0 << endl;
// cout << "2" << " " << cur_day<< endl;
}
}
}
while(cur_day <= n) {
cout << 0 << endl;
cur_day++;
}
return 0;
}
