#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define sz(x) (int)x.size()
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int N, D, M; cin >> N >> D >> M;
map<int, vector<int>> vals;
for (int i = 1; i <= M; ++i) {
int num; cin >> num;
vals[num].push_back(i);
}
int left = 1; int right = 1e6;
while (left < right) {
int mid = left + (right - left) / 2;
ll curr = 0; int del = 0;
for (auto val : vals) {
curr += sz(val.second);
if (!sz(val.second)) curr += mid;
del = max(del, (int)ceil(curr / mid) - val.first);
}
if (del > D) {
left = mid + 1;
} else {
right = mid;
}
}
cout << left << '\n';
int ctr = 0; vector<vector<int>> ans(N);
for (auto val : vals) {
for (int num : val.second) {
if (sz(ans[ctr]) >= left) ++ctr;
ans[ctr].push_back(num);
}
}
for (vector<int> day : ans) {
for (int req : day) {
cout << req << " ";
}
cout << 0 << '\n';
}
}
