// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>
using namespace std;
#define nl '\n'
#define pb push_back
#define sz(x) int(x.size())
template<class T> using V = vector<T>;
int main() {
cin.tie(0)->sync_with_stdio(0);
int N, D, M; cin >> N >> D >> M;
V<V<int>> C(N); for(int i = 0; i < M; i++) {
int t; cin >> t; --t;
C[t].pb(i);
}
V<V<int>> ans(N);
queue<pair<int, int>> in;
auto check = [&](int x) -> bool {
ans = V<V<int>>(N);
in = {};
for(int i = 0; i < N; i++) {
if (sz(in) && in.front().first <= i) return 0;
int end = i + D + 1;
for(auto& c : C[i]) in.push(pair<int, int>{end, c});
int left = x;
while(left-- && sz(in)) {
ans[i].push_back(in.front().second);
in.pop();
}
}
return sz(in) == 0;
};
int lo = 0, hi = M + 1;
while(lo < hi) {
int mid = (lo + hi) / 2;
if (check(mid)) hi = mid;
else lo = mid + 1;
}
check(lo);
cout << lo << nl;
for(int i = 0; i < N; i++) {
for(auto x : ans[i]) cout << x + 1 << " ";
cout << 0 << nl;
}
cout << nl;
return 0;
}
