#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
struct Node{int val, lazy, ptr, lptr;};
struct Seg{
int N;
vector<Node> t;
Seg(int n): N(n), t(4*n+4, {0,0,0,-1}) {}
void prop(int nd, int st, int ed){
if(t[nd].lazy == 0) return;
if(t[nd].val < t[nd].lazy){
t[nd].val = t[nd].lazy;
t[nd].ptr = t[nd].lptr;
}
if(st != ed){
int L = nd<<1, R = L|1;
if(t[L].lazy < t[nd].lazy){
t[L].lazy = t[nd].lazy;
t[L].lptr = t[nd].lptr;
}
if(t[R].lazy < t[nd].lazy){
t[R].lazy = t[nd].lazy;
t[R].lptr = t[nd].lptr;
}
}
t[nd].lazy = 0;
t[nd].lptr = -1;
}
void upd(int l, int r, int x, int p){
struct F{int nd, st, ed, l, r, x, p, stage, md;};
vector<F> stk;
stk.reserve(80);
stk.push_back({1, 1, N, l, r, x, p, 0, 0});
while(!stk.empty()){
auto &f = stk.back();
if(f.stage==0){
prop(f.nd, f.st, f.ed);
if(f.r< f.st || f.ed < f.l){
stk.pop_back();
continue;
}
if(f.l <= f.st && f.ed <= f.r){
if(t[f.nd].lazy < f.x){
t[f.nd].lazy = f.x;
t[f.nd].lptr = f.p;
}
prop(f.nd, f.st, f.ed);
stk.pop_back();
}
else{
f.md = (f.st+f.ed)>>1;
f.stage = 1;
stk.push_back({f.nd*2+1, f.md+1, f.ed, f.l, f.r, f.x, f.p, 0, 0});
stk.push_back({f.nd*2, f.st, f.md, f.l, f.r, f.x, f.p, 0, 0});
}
}
else{
stk.pop_back();
}
}
}
int gt(int l, int r){
struct F{int nd, st, ed, l, r, stage, md;};
vector<F> stk;
stk.reserve(80);
stk.push_back({1, 1, N, l, r, 0, 0});
int res = 0;
while(!stk.empty()){
auto &f = stk.back();
if(f.stage == 0){
prop(f.nd, f.st, f.ed);
if(f.r < f.st || f.ed < f.l){
stk.pop_back();
continue;
}
if(f.l <= f.st && f.ed <= f.r){
res = max(res, t[f.nd].val);
stk.pop_back();
}
else{
f.md = (f.st+f.ed)>>1;
f.stage = 1;
stk.push_back({f.nd*2+1, f.md+1, f.ed, f.l, f.r, 0, 0});
stk.push_back({f.nd*2, f.st, f.md, f.l, f.r, 0, 0});
}
}
else{
stk.pop_back();
}
}
return res;
}
int gp(int p){
struct F{int nd, st, ed, p;};
vector<F> stk;
stk.reserve(80);
stk.push_back({1, 1, N, p});
int ans = 0;
while(!stk.empty()){
auto f = stk.back(); stk.pop_back();
prop(f.nd, f.st, f.ed);
if(f.st == f.ed){
ans = t[f.nd].ptr;
}
else{
int md = (f.st+f.ed)>>1;
if(f.p <= md) stk.push_back({f.nd*2, f.st, md, f.p});
else stk.push_back({f.nd*2+1, md+1, f.ed, f.p});
}
}
return ans;
}
};
int n;
array<int, 2> a[1000006];
int main(){
int n;
scanf("%d", &n);
for(int i=2; i<=n+1; i++){
scanf("%d", &a[i][0]);
a[i][1] = i-1;
}
sort(a+2, a+n+2, greater<>());
Seg seg(n+1);
seg.upd(1, 1, 1, 1);
for(int i=2; i<=n+1; i++){
int L = i+a[i][0]-1;
int R = n+1;
int pre = seg.gt(i-1, i-1);
if(pre > 0) seg.upd(L, R, pre+1, i);
}
int res = seg.gt(n+1, n+1)-1;
int tp = n;
int sum = 0;
int cnt = 0;
while(tp > 1){
int l = seg.gp(tp);
if(l-1 <= 2) break;
if(tp-l+1 >= a[2][0]){
sum += tp-l+1;
cnt++;
}
tp = l-1;
}
int l = a[2][0]-1, r = max(cnt ? sum/cnt : 1, (tp-1)), gap = 1;
while(l <= r){
int md = (l+r)/2;
fill(seg.t.begin(), seg.t.end(), Node{0, 0, 0, -1});
seg.upd(1, 1, 1, 1);
for(int i=2; i<=n+1; i++){
int L = i+a[i][0]-1;
int R = min(i+md, n+1);
int pre = seg.gt(i-1, i-1);
if(pre > 0) seg.upd(L, R, pre+1, i);
}
if(seg.gt(n+1, n+1)-1 == res){
gap = md;
r = md-1;
}
else{
l = md+1;
}
}
fill(seg.t.begin(), seg.t.end(), Node{0, 0, 0, -1});
seg.upd(1, 1, 1, 1);
for(int i=2; i<=n+1; i++){
int L = i+a[i][0]-1;
int R = min(i+gap, n+1);
int pre = seg.gt(i-1, i-1);
if(pre > 0) seg.upd(L, R, pre+1, i);
}
printf("%d\n", res);
int cp = n+1;
while(cp > 1){
int l = seg.gp(cp);
printf("%d", cp-l+1);
for(int i=l; i<=cp; i++){
printf(" %d", a[i][1]);
}
cp = l-1;
printf("\n");
}
}
