#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;
int n, d, m;
vi requestsOnDay[(int)1e6 + 1];
int jobs[(int)1e6 + 1];
bool check(int machines)
{
queue<int> active;
for (int i = 1; i <= n; i++)
{
// get new requests
for (int id : requestsOnDay[i])
active.push(id);
int mm = machines;
while (!active.empty() && mm--)
{
int id = active.front();
if (jobs[id] + d < i)
return false;
else
active.pop();
}
}
return active.empty();
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> d >> m;
for (int i = 0; i < m; i++)
{
int x;
cin >> x;
jobs[i] = x;
requestsOnDay[x].pb(i);
}
int lo = 1, hi = m;
while (lo < hi)
{
int mid = (lo + hi) / 2;
if (check(mid))
hi = mid;
else
lo = mid + 1;
}
cout << lo << '\n';
vvi onDay(n + 1);
queue<int> active;
for (int i = 1; i <= n; i++)
{
// get new requests
for (int id : requestsOnDay[i])
active.push(id);
int mm = lo;
while (!active.empty() && mm--)
{
int id = active.front();
onDay[i].pb(id);
active.pop();
}
}
for (int i = 1; i <= n; i++)
{
for (int id : onDay[i])
cout << id + 1 << " ";
cout << "0\n";
}
}
