#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define all(s) s.begin(), s.end()
#ifndef LOCALDEBUG
#define LOCALDEBUG false
#endif
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> pii;
struct request
{
int day, id;
bool operator<(const request &a)
{
return day < a.day;
}
};
int n, d, m;
request jobs[(int)1e6 + 1];
bool check(int machines)
{
int nxt = 0;
for (int i = 1; i <= n; i++)
{
int mm = machines;
while (nxt < m && mm--)
{
request cur = jobs[nxt];
if (cur.day + d < i)
return false;
else
nxt++;
}
}
return nxt == m;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> d >> m;
for (int i = 0; i < m; i++)
{
cin >> jobs[i].day;
jobs[i].id = i;
}
sort(jobs, jobs + m);
int lo = 1, hi = 1e6;
while (lo < hi)
{
int mid = (lo + hi) / 2;
if (check(mid))
hi = mid - 1;
else
lo = mid + 1;
}
cout << lo << '\n';
vvi onDay(n + 1);
int nxt = 0;
for (int i = 1; i <= n; i++)
{
int mm = lo;
while (nxt < m && mm--)
onDay[i].pb(jobs[nxt++].id);
}
for (int i = 0; i < n; i++)
{
for (int id : onDay[i + 1])
cout << id + 1 << " ";
cout << "0\n";
}
}
