#define _CRT_SECURE_NO_WARNINGS 1
#include<bits/stdc++.h>
#include <array>
#include<unordered_map>
#include<unordered_set>
using namespace std;
#define double long double
#define int long long
#define lc u<<1
#define rc u<<1|1
//#define endl "\n"
#define X first
#define Y second
//typedef unsigned long long ll;
typedef long long ll;
typedef pair<ll, ll> PII;
const long long N = 1e6 + 50, M = 2e5 + 5, INF = 0x3f3f3f3f;
const long long maxm = 1e18 + 5, maxn = 3e5 + 5;
//const ll maxm = LLONG_MAX;
const long long mod = 998244353;
//const ll mod = 1e9 + 7;
ll dx[] = { -1,0,1,0 };
ll dy[] = { 0,1,0,-1 };
//__builtin_popcountll();
//a.erase(unique(a.begin(),a.end()),a.end());//去重
//string demo = str.substr(ps,(r-l+1));//截取下标从ps开始的长度为len子串
//找第一次出现的字符的下标也用.find吧
//字符串陋习，尽可能这样获取子串，直接+=会t
ll exgcd(ll a, ll b, ll& x, ll& y);
inline ll gcd(ll a, ll b) {
return b > 0 ? gcd(b, a % b) : a;
}
ll ksm(ll a, ll b, ll p) {
ll base = a;
ll ans = 1;
while (b) {
if (b & 1)ans *= base;
ans %= p;
base *= base; base %= p;
b >>= 1;
}
return ans % p;
}
void KKLK(ll a, ll b, ll c, ll d) {
cout << "[ " << a << "," << b << "," << c << "," << d << " ]" << endl;
}
/*
struct cmp {
bool operator()(node a, node b) {
return a.d > b.d;//表示小根堆
}
};*/
ll n, d, m;
pair<ll, ll>a[N];
bool check(ll k) {
ll now = 1;
for (int i = 1; i <= m; i++) {
if (now > n)return false;
ll nxt = i + k;
nxt = min(nxt, m + 1);
if (a[i].X + d >= now) {
}
else return false;
++now; i = nxt - 1;
}
return true;
}
void solve() {
//显然二分
cin >> n >> d >> m; for (int i = 1; i <= m; i++)cin >> a[i].X, a[i].Y = i;
sort(a + 1, a + 1 + m);
ll l = 0, r = m;
while (l + 1 < r) {
ll mid = l + r >> 1;
if (check(mid)) {
r = mid;
}
else l = mid;
}
cout << r << endl;
ll now = 1;
for (int i = 1; i <= m; i++) {
ll nxt = i + r;
nxt = min(nxt, m + 1);
for (int j = i; j < nxt; j++)cout << a[j].Y << ' ';
cout << 0 << endl;
++now; i = nxt - 1;
}
while (now <= n) {
cout << 0 << endl; ++now;
}
}
signed main() {
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
ll _t = 1; //cin >> _t;
while (_t--)solve();
return 0;
}
/*PonyHex*/
/*SilverWolf__*/
ll exgcd(ll a, ll b, ll& x, ll& y) {
if (b == 0) {
x = 1; y = 0;
return a;
}
ll g = exgcd(b, a % b, x, y);
ll temp = x;
x = y;
y = temp - (a / b) * y;
return g;
}
