#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(),v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define oo (ll)1e18 + 10
#define INF (ll)1e9
#define MOD (ll)(998244353)
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2>
void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}
template<class T1, class T2>
void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}
template<class T>
void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}
const int MAX = 1e6 + 10;
int N, D, M;
pair<int, int> a[MAX];
int ans[MAX];
void solve(){
cin >> N >> D >> M;
for(int i = 1; i <= M; i++){
cin >> a[i].fi;
a[i].se = i;
}
sort(a + 1, a + M + 1);
auto OK = [&](int k) -> bool{
int day = 1, cnt = 0;
for(int i = 1; i <= M; i++){
if(day - a[i].fi > D) return false;
if(maximize(day, a[i].fi)) cnt = 0;
cnt++;
ans[a[i].se] = day;
if(cnt == k){
day++;
cnt = 0;
}
}
return true;
};
int l = 1, r = M;
while(l < r){
int m = (l + r) >> 1;
if(OK(m)) r = m;
else l = m + 1;
}
OK(r);
cout << r << '\n';
vector<vector<int>> trace(N + 3);
for(int i = 1; i <= M; i++){
trace[ans[i]].push_back(i);
}
for(int i = 1; i <= N; i++){
for(int x: trace[i]) cout << x << ' ';
cout << 0 << '\n';
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("task.inp","r",stdin);
// freopen("task.out","w",stdout);
int T = 1;
// cin >> T;
for(; T; T--) solve();
return 0;
}
