#include <bits/stdc++.h>
#define int long long
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define REV(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
using namespace std;
#define MAXN 100005
int n, d, m;
vector<int> task[MAXN];
vector<int> res[MAXN];
deque<pair<int, int>> in_queue;
struct BIT {
int n;
vector<int> bit;
BIT(int _n = 0){
n = _n;
bit.assign(n + 5, 0);
}
void upd(int p, int val){
for (; p <= n; p += p & -p) bit[p] += val;
}
int get(int x) {
int res = 0;
while (x) res += bit[x], x -= x & -x;
return res;
}
int get(int u, int v) {
return get(v) - get(u - 1);
}
} robot;
int Find(int l, int r){
int lo = l, hi = r, ans = -1;
while (lo <= hi){
int mid = (lo + hi) >> 1;
if (robot.get(l, mid) > 0){
ans = mid;
hi = mid - 1;
} else lo = mid + 1;
}
return ans;
}
void solve(){
cin >> n >> d >> m;
FOR(i, 1, m){
int x; cin >> x;
task[x].push_back(i);
}
robot = BIT(n);
int need_robot = 0;
FOR(i, 1, n){
for (int &x : task[i]){
int closest = Find(i, i + d);
if (closest == -1){
need_robot++;
res[i].push_back(x);
robot.upd(i + 1, 1);
} else {
robot.upd(closest, -1);
res[closest].push_back(x);
robot.upd(closest + 1, 1);
}
}
}
cout << need_robot << '\n';
FOR(i, 1, n){
for (int &x : res[i]) cout << x << ' ';
cout << 0 << '\n';
}
}
/**
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
5 3 6
1 1 1 1 1 1
**/
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
solve();
return 0;
}
