#include<bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define sz(x) (int) (x).size()
#define MASK(n) (1 << (n))
#define BIT(mask,x) ((mask >> (x)) & 1)
#define TASK "task"
using namespace std;
const int mxN = 1e6 + 7;
const int base = 512;
const int inf = 1e9 + 6969;
const int Mod = 1e9 + 7;
const long long infll = 1e18 + 6969;
template <typename T1, typename T2> bool minimize(T1 &a, T2 b) {
if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maximize(T1 &a, T2 b) {
if (a < b) {a = b; return true;} return false;
}
#define int long long
int n;
int d;
int m;
pair<int,int>a[mxN];
bool ok(int num_machine) {
int j = 1;
int cnt;
for (int i = 1; i <= n; i++) {
cnt = 0;
if(a[j].fi + d < i) {
//cout << i << " " << j << "\n";
return false;
}
while(cnt < num_machine && a[j].fi <= i && j <= m) {
cnt++;
j++;
}
if(j > m) return true;
}
return false;
}
void tracing(int num_machine) {
int j = 1;
int cnt;
for (int i = 1; i <= n; i++) {
cnt = 0;
while(cnt < num_machine && a[j].fi <= i && j <= m) {
cnt++;
cout << a[j].se << " ";
j++;
}
cout << 0 << '\n';
}
}
void solve() {
cin >> n >> d >> m;
for (int i = 1; i <= m; i++) cin >> a[i].fi,a[i].se = i;
sort(a + 1,a + m + 1);
int lo = 1,hi = max(n,m),ans = 0;
while(lo <= hi) {
int mid = (lo + hi) >> 1;
if(ok(mid)) {
ans = mid;
hi = mid - 1;
}else lo = mid + 1;
}
cout << ans << "\n";
tracing(ans);
}
signed main() {
ios_base :: sync_with_stdio(0);
cin.tie(0);
int tc = 1;
//cin >> tc;
while(tc--) {
solve();
}
}
