#include <bits/stdc++.h>
#define int long long
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define REV(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
using namespace std;
#define MAXN 100005
int n, d, m;
vector<int> task[MAXN];
vector<int> res[MAXN];
bool g(int x){
deque<pair<int, int>> dq;
FOR(i, 1, n){
if (task[i].size()) dq.push_back(make_pair(i + d, task[i].size()));
int take = x;
while (take > 0 && dq.size()) {
pair<int, int> tmp = dq.front();
dq.pop_front();
if (take >= tmp.second) {
take -= tmp.second;
} else {
tmp.second -= take;
take = 0;
dq.push_front(tmp);
}
}
if (dq.size() && dq.front().first <= i) return false;
}
return true;
}
void solve(){
cin >> n >> d >> m;
FOR(i, 1, m){
int x; cin >> x;
task[x].push_back(i);
}
int lo = 1, hi = m, ans = hi;
while (lo <= hi){
int mid = (lo + hi) >> 1;
if (g(mid)){
ans = mid;
hi = mid - 1;
} else lo = mid + 1;
}
cout << ans << '\n';
deque<int> process;
FOR(i, 1, n){
for (int &x : task[i]) process.push_back(x);
int take = ans;
while (take > 0 && process.size()){
take--;
res[i].push_back(process.front());
process.pop_front();
}
}
FOR(i, 1, n){
for (int &x : res[i]) cout << x << ' ';
cout << "0\n";
}
}
/**
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
6 3 6
1 1 1 1 1 1
**/
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
solve();
return 0;
}
