#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define MOD 1000000007
#define MODA 998244353
#define pb push_back
#define sortv(v) sort(v.begin(), v.end())
#define sorta(A, N) sort(A, A + N)
#define debug(x) cerr << #x << " is " << x;
#define rep(i, a, N) for (ll i = a; i < N; i++)
#define f first
#define s second
#define uniq(v) \
{ \
sort(v.begin(), v.end()); \
v.erase(unique(v.begin(), v.end()), v.end()); \
}
#define speed \
ios_base::sync_with_stdio(false); \
cin.tie(NULL); \
cout.tie(NULL);
using namespace std;
pair<bool, vector<vector<ll> > > check(const vector<pair<ll, ll> > &a, ll machines, ll N, ll D)
{
vector<vector<ll> > sched(N);
ll pos = 0, flag = 1, M = a.size();
rep(day, 1, N + 1)
{
rep(machine, 0, machines)
{
if (a[pos].f > day)
break;
if (a[pos].f + D >= day)
sched[day - 1].pb(a[pos++].s);
else
{
return make_pair(false, sched);
}
if (pos == M)
return make_pair(true, sched);
}
}
return make_pair(false, sched);
}
void solve(ll tcase)
{
ll N, D, M;
cin >> N >> D >> M;
vector<pair<ll, ll> > a(M);
rep(i, 0, M)
{
cin >> a[i].f;
a[i].s = i;
}
sortv(a);
ll lo = 1, hi = M + 1;
pair<bool, vector<vector<ll> > > p;
while (lo < hi)
{
ll mid = (lo + hi) / 2;
p = check(a, mid, N, D);
if (p.f)
hi = mid;
else
lo = mid + 1;
}
cout << hi << "\n";
p = check(a, hi, N, D);
rep(i, 0, N)
{
for (auto j : p.s[i])
cout << j + 1 << ' ';
cout << "0\n";
}
}
int main()
{
speed;
ll t = 1;
rep(i, 1, t + 1)
solve(i);
}
