#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#ifdef DEBUG
#include <time.h>
#endif
#define all(a) (a).begin(), (a).end()
#define rev(a) (a).rbegin(), (a).rend()
#define F first
#define S second
int recur_depth = 0;
#ifdef DEBUG
#define dbg(x) \
{ \
++recur_depth; \
auto x_ = x; \
--recur_depth; \
cerr << string(recur_depth, '\t') << "\e[91m" << __func__ << ":" \
<< __LINE__ << "\t" << #x << " = " << x_ << "\e[39m" << endl; \
}
#else
#define dbg(x)
#endif
using namespace std;
using namespace __gnu_pbds;
typedef pair<int, int> ii;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> llll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pair<int, int>> vii;
typedef vector<vii> vvii;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pair<ll, ll>> vll;
typedef vector<vll> vvll;
typedef vector<bool> vb;
template <class type1>
using ordered_set = tree<type1, null_type, less<type1>, rb_tree_tag,
tree_order_statistics_node_update>;
template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p) {
return os << '(' << p.first << ", " << p.second << ')';
}
template <typename T_container, typename T = typename enable_if<
!is_same<T_container, string>::value,
typename T_container::value_type>::type>
ostream &operator<<(ostream &os, const T_container &v) {
os << '{';
string sep;
for (const T &x : v)
os << sep << x, sep = ", ";
return os << '}';
}
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll INF = 1e9;
const ld EPS = 1e-9;
void solve() {
int n, d, m;
cin >> n >> d >> m;
vii as(m);
for (auto &[x, _] : as)
cin >> x;
for (int i = 0; i < m; i++)
as[i].second = i;
sort(all(as));
auto check = [&](int no_mc) {
priority_queue<ii, vii, greater<ii>> s;
int m_idx = 0;
for (int day = 1; day <= n; day++) {
while (m_idx < m && as[m_idx].first == day)
s.push(as[m_idx++]);
for (int cnt = 0; cnt < no_mc; cnt++)
if (s.size()) {
auto [curr, _] = s.top();
s.pop();
if (day > curr + d)
return false;
}
}
return s.empty();
};
int l = 1, r = m - 1, ans = m;
while (l <= r) {
int mid = (l + r) / 2;
if (check(mid)) {
r = mid - 1;
ans = mid;
} else
l = mid + 1;
}
vvi on(n + 1);
priority_queue<ii, vii, greater<ii>> s;
int m_idx = 0;
for (int day = 1; day <= n; day++) {
while (m_idx < m && as[m_idx].first == day)
s.push(as[m_idx++]);
for (int cnt = 0; cnt < ans; cnt++)
if (s.size()) {
ii curr = s.top();
s.pop();
on[day].push_back(curr.second);
assert(day <= curr.first + d);
}
}
cout << ans << "\n";
for (int i = 1; i <= n; i++) {
for (int &x : on[i])
cout << x + 1 << " ";
cout << "0\n";
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
clock_t start = clock();
int test_cases = 1;
// cin >> test_cases;
while (test_cases--)
solve();
#ifdef DEBUG
cerr << fixed << setprecision(10)
<< "\nTime Taken: " << (double)(clock() - start) / CLOCKS_PER_SEC
<< "s\n";
#endif
return 0;
}
