#include <iostream>
#include <vector>
#include <algorithm>
using namespace::std;
#define FOR(i, b) for(int i = 0; i < b; i++)
typedef vector<int> vint;
typedef vector<vint> v2d;
struct req{ int r, id;
bool operator<(const req& o)const{ return r < o.r; }};
int N, D, M;
vector<req> reqs;
v2d days;
bool can(int m){ //can i make all requests with m machines
days = v2d(N);
int day = 1, m_i = 0;
FOR(i, M){
if(reqs[i].r > day){ day = reqs[i].r; m_i = 0;} //cant start till on submission date
if(day > reqs[i].r + D) return false; //done after delay
days[day-1].push_back(reqs[i].id);
m_i++; //used this machine
if(m_i == m){ day++; m_i = 0; } //all machines that day used up
}
return true;
}
int main() {
cin>>N>>D>>M;
reqs.resize(M);
FOR(i, M) { cin>>reqs[i].r; reqs[i].id = i+1; }
sort(reqs.begin(), reqs.end());
//binary search on # of machines ---++
int lo = 1, hi = 1e6;
while(lo != hi){
int mid = (lo+hi)/2;
if(can(mid)) hi = mid;
else lo = mid+1;
}
//print answer
can(lo);
cout<<lo<<endl;
FOR(i, N){
for(int r : days[i]) cout<<r<<" ";
cout<<0<<endl;
}
}
