#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int N, D, M;
cin >> N >> D >> M;
vector<int> A(M);
for(int i = 0; i < M; i++) {
cin >> A[i];
}
vector<int> order(M);
iota(order.begin(), order.end(), 1);
sort(order.begin(), order.end(), [&](int i, int j) -> bool { return A[i - 1] > A[j - 1]; });
sort(A.begin(), A.end(), greater<int>());
int lo = 1, hi = M;
while(lo < hi) {
int mid = lo + (hi - lo) / 2;
int mx_d = 0, day = 1;
vector<int> B = A;
while(!B.empty()) {
int mu = 0;
while(mu < mid && !B.empty() && B.back() <= day) {
mx_d = max(mx_d, day - B.back());
B.pop_back();
mu++;
}
day++;
}
if(mx_d <= D) {
hi = mid;
}
else {
lo = mid + 1;
}
}
vector<vector<int>> ans(N);
int day = 1;
while(!A.empty()) {
int mu = 0;
while(mu < lo && !A.empty() && A.back() <= day) {
ans[day - 1].push_back(order.back());
A.pop_back();
order.pop_back();
mu++;
}
ans[day - 1].push_back(0);
day++;
}
cout << lo << '\n';
for(int i = 0; i < N; i++) {
if(ans[i].empty()) {
cout << "0\n";
continue;
}
for(int j = 0; j < (int)ans[i].size(); j++) {
cout << ans[i][j] << " \n"[j == (int)ans[i].size() - 1];
}
}
return 0;
}
