#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=401000;
int p[N],n,t,nxt[N];
VI v[N],son[N];
vector<PII> ans;
int dfs(int u) {
	if (SZ(son[u])==0) {
		v[++t]={u,u,nxt[u]};
		return t;
	} else {
		VI meg;
		for (auto v:son[u]) {
			meg.pb(dfs(v));
		}
		VI pre=v[meg[0]];
		v[++t]={u,pre[0],pre[1],pre[2]};
		ans.pb({t,meg[0]});
		v[++t]={u,pre[1],pre[2]};
		ans.pb({t,t-1});
		int rid=t;
		rep(i,1,SZ(meg)) {
			VI cur=v[meg[i]];
			v[++t]={u,cur[0],cur[1],cur[2]};
			ans.pb({t,meg[i]});
			v[++t]={u,cur[1],cur[2]};
			ans.pb({t,t-1});
			//printf("pre %d %d %d\n",pre[0],pre[1],pre[2]);
			//printf("cur %d %d %d\n",cur[0],cur[1],cur[2]);
			assert(pre[2]==cur[1]);
			v[++t]={u,pre[1],pre[2],cur[2]};
			ans.pb({t,rid});
			ans.pb({t,t-1});
			v[++t]={u,pre[1],cur[2]};
			ans.pb({t,t-1});
			pre=v[t];
			rid=t;
		}
		return rid;
	}
}

int main() {
	scanf("%d",&n);
	rep(i,2,n+1) {
		scanf("%d",&p[i]);
		son[p[i]].pb(i);
	}
	VI lef;
	rep(i,1,n+1) if (son[i].empty()) {
		lef.pb(i);
	}
	rep(i,0,SZ(lef)) nxt[lef[i]]=lef[(i+1)%SZ(lef)];
	dfs(1);
	printf("%d\n",t);
	assert(SZ(ans)==t-1);
	rep(i,1,t+1) {
		set<int> ps(all(v[i]));
		printf("%d ",SZ(ps));
		for (auto x:ps) printf("%d ",x); puts("");
	}
	for (auto [u,v]:ans) printf("%d %d\n",u,v);
}