#include "bits/stdc++.h"
using namespace std;
#define endl "\n"
#define ll long long int
#define pb push_back
#define mp make_pair
#define fi first
#define se second
const long long MOD = 1e9+7;
const long long INF = 1e18;
int nx[4] = {0, 0, -1, 1};
int ny[4] = {1, -1, 0, 0};
vector<vector<ll>> RES;
bool f(queue<pair<ll, ll>> q, ll d, ll mid, ll n)
{
vector<vector<ll>> temp;
temp.assign(n, {});
ll currd = 1;
ll c = mid;
while(!q.empty())
{
if(c==0)
{
currd++;
c = mid;
}
ll task = q.front().fi;
ll id = q.front().se;
if(currd<task)
{
currd = task;
c = mid;
}
if(currd>task+d)
{
return false;
}
q.pop();
c--;
temp[currd-1].pb(id);
}
RES = temp;
return true;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
ll n, d, m;
cin >> n >> d >> m;
RES.assign(n, {});
vector<pair<ll, ll>> arr;
for(int i = 0; i<m; i++)
{
ll x;
cin >> x;
arr.pb(mp(x, i+1));
}
sort(arr.begin(), arr.end());
vector<ll> occ(n+1, 0);
queue<pair<ll, ll>> q;
for(int i = 0; i<m; i++)
{
occ[arr[i].fi]++;
q.push(arr[i]);
}
ll lim = 0;
for(int i = 0; i<=n; i++)
{
lim = max(lim, occ[i]);
}
ll l = 0; //l is bad
ll r = lim+1; //r is good
while(l+1<r)
{
ll mid = (l+r)/2;
if(f(q, d, mid, n))
{
r = mid;
}
else
{
l = mid;
}
}
cout << r << endl;
for(int i = 0; i<n; i++)
{
for(auto elt: RES[i])
cout << elt << ' ';
cout << 0 << endl;
}
return 0;
}
