#include <bits/stdc++.h>
using namespace std;
#define ld long double
#define int long long
#define ar array
const int N = 1e6 + 20;
int n, d, m;
ar<int, 2> A[N];
bool check(int x){
int l = 0, r = 0;
for(int i = 1;i <= n;i++){
//cout<<l<<" "<<r<<'\n';
while(r < m && A[r][0] == i)++r;
if(l != r && l < m && i - A[l][0] > d)return 0;
l = min(l + x, r);
}
return l == r && r== m;
}
void print(int x){
int l = 0, r = 0;
for(int i = 1;i <= n;i++){
while(r < m && A[r][0] == i)++r;
for(;l < min(l + x, r);l++){
cout<<A[l][1]<<' ';
}
cout<<"0"<<endl;
++l;
}
}
signed main() {ios_base::sync_with_stdio(false);cin.tie(0);
cin>>n>>d>>m;
for(int i = 0;i < m;i++){
cin>>A[i][0];
A[i][1] = 1 + i;
}
sort(A, A + m);
int lo = 1, hi = m;
int ans = m;
//cout<<check(7);
while(lo <= hi){
//cout<<lo<<" "<<hi<<endl;
int mid = (lo + hi) / 2;
if(check(mid)){
ans = mid;
hi = mid - 1;
}else lo = mid + 1;
}
cout<<ans<<endl;
print(ans);
}
