#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}());
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head
const int N=1010000;
int n,d,m,a[N];
VI qs[N];
bool check(int x) {
deque<int> dq;
rep(i,1,n+1) {
for (auto x:qs[i]) dq.pb(i+d);
rep(j,0,min(SZ(dq),x)) {
if (dq[0]<i) return false;
dq.pop_front();
}
}
return dq.empty();
}
void rec(int x) {
deque<int> dq;
rep(i,1,n+1) {
for (auto x:qs[i]) dq.pb(x);
rep(j,0,min(SZ(dq),x)) {
printf("%d ",dq[0]);
dq.pop_front();
}
printf("0\n");
}
}
int main() {
scanf("%d%d%d",&n,&d,&m);
rep(i,1,m+1) scanf("%d",a+i),qs[a[i]].pb(i);
int l=1,r=m,ans=0;
while (l<=r) {
int md=(l+r)>>1;
if (check(md)) ans=md,r=md-1;
else l=md+1;
}
printf("%d\n",ans);
rec(ans);
}
/*
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
*/
