#include <bits/stdc++.h>
using namespace std;
vector<vector<int>> a;
int m,n,d,res;
bool check(int k)
{
if(k <= 0)return 0;
int cnt = 0;
for(int i = 1; i <= n; i++){
if(i <= n-d)cnt += (int)a[i].size();
cnt = (cnt > k) ? cnt-k : 0;
if(cnt == 0 && i > n-d)break;
}
return (cnt == 0);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
cin >> n >> d >> m;
a = vector<vector<int>> (n-d+1);
for(int i = 0; i < m; i++){
int tmp; cin >> tmp;
a[tmp].push_back(i+1);
}
int l = 0, r = m;
while(l < r){
int mid = (l+r) >> 1;
if(check(mid))r = mid;
else l = mid+1;
}
for(int i = l-1; i <= l+1; i++){
if(check(i)){
res = i;
break;
}
}
cout << res << '\n';
queue<int> q;
for(int i = 1; i <= n; i++){
if(i <= n-d){
for(int j : a[i])
q.push(j);
}
if(!q.empty())
for(int j = 0; j < res; j++){
cout << q.front() << ' ';
q.pop();
if(q.empty())break;
}
cout << 0 << '\n';
}
return 0;
}
