#include <bits/stdc++.h>
#define ll long long
using namespace std;
bool f(int machines, vector<vector<int>>& result, vector<pair<int,int>>& v, int delay, int n)
{
int ptr = 1;
for(int i=1;i<=n;i++)
{
for(int j=0;j<machines;j++)
{
if(v[ptr].first > i) // we need to go to ahead day because now tasks are assigned at days v[ptr].first or later
break;
if(v[ptr].first + delay >= i)
{
result[i].push_back(v[ptr].second);
ptr++;
}
else return false;
if(ptr==v.size()) return true;
}
}
return true;
}
int main() {
int n,d,m;
cin>>n>>d>>m;
vector<pair<int,int>> v(m+1);
for(int i=1;i<=m;i++)
{
int start;
cin>>start;
v[i] = {start,i};
}
sort(v.begin(),v.end());
vector<vector<int>> result(n+1);
int l=1,r=m;
while(l<=r)
{
int mid = l + (r-l)/2;
vector<vector<int>> temp(n+1);
if(f(mid,temp,v,d,n))
{
r=mid-1;
result = temp;
}
else l=mid+1;
}
cout<<l<<'\n';
for(int i=1;i<=n;i++)
{
for(int j=0;j<result[i].size();j++)
{
cout<<result[i][j]<<" ";
}
cout<<"0\n";
}
}
