#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
int n, m, d; pair<int, int> tasks[1000005];
bool check(int mid){
int pos = 1;
for(int i = 1; i <= n; i++) for(int j = 1; j <= mid && pos <= m && tasks[pos].ff <= i; j++) if(i - tasks[pos++].ff > d) return 0;
return (pos == m + 1);
}
int main(){
cin >> n >> m >> d;
for(int i = 0; i < m; i++) {cin >> tasks[i].ff; tasks[i].ss = i;}
sort(tasks + 1, tasks + m + 1);
int l = 1, r = m + 1;
while(l < r){
int mid = (l + r) / 2;
if(check(mid)) r = mid; else l = mid + 1;
}
cout << r << '\n';
int pos = 1;
for(int i = 1; i <= n; i++){
for(int j = 1; j <= r && pos <= m && tasks[pos].ff <= i; j++, pos++) cout << tasks[pos].ss << ' ';
cout << 0 << '\n';
}
}
