#include <bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define X first
#define Y second
const int N=1e5+5;
int n,D,request,x,l,r,mid,res,remain;
vector <int> pos[N];
deque <int> dq;
bool check(int mid)
{
int remain;
queue <pii> q;
for (int i=1;i<=n;i++)
{
q.push(make_pair(i,pos[i].size()));
remain=mid;
while (!q.empty())
{
x=min(remain,q.front().Y);
remain-=x;
q.front().Y-=x;
if (q.front().Y==0) q.pop();
if (remain==0) break;
}
if (!q.empty() and q.front().X<=i-D) return false;
}
return true;
}
int main()
{
ios_base::sync_with_stdio(NULL);
cin.tie(NULL); cout.tie(NULL);
cin >> n >> D >> request;
for (int i=1;i<=request;i++)
{
cin >> x;
pos[x].push_back(i);
}
l=1;
r=1e9;
res=0;
while (l<=r)
{
mid=(l+r)/2;
if (check(mid))
{
r=mid-1;
res=mid;
}
else l=mid+1;
}
cout << res << '\n';
dq.clear();
for (int i=1;i<=n;i++)
{
for (int j:pos[i])
dq.push_back(j);
remain=res;
while (!dq.empty() and remain)
{
remain--;
cout << dq.front() << ' ';
dq.pop_front();
}
cout << 0 << '\n';
}
}
