1 /*************************************************************************
 2     > File Name: 可持久化链式前向星
 3     > Author: QWX
 4     > Mail:
 5     > Created Time: 2018/10/8 19:49:24
 6  ************************************************************************/
 7
 8
 9 //{{{ #include
10 #include<iostream>
11 #include<cstdio>
12 #include<algorithm>
13 #include<vector>
14 #include<cmath>
15 #include<queue>
16 #include<map>
17 #include<set>
18 #include<string>
19 #include<cstring>
20 #include<complex>
21 #include<bits/stdc++.h>
22 #define mp make_pair
23 #define pb push_back
24 #define first fi
25 #define second se
26 #define pw(x) (1ll << (x))
27 #define sz(x) ((int)(x).size())
28 #define all(x) (x).begin(),(x).end()
29 #define rep(i,l,r) for(int i=(l);i<(r);i++)
30 #define per(i,r,l) for(int i=(r);i>=(l);i--)
31 #define FOR(i,l,r) for(int i=(l);i<=(r);i++)
32 #define eps 1e-9
33 #define PIE acos(-1)
34 #define cl(a,b) memset(a,b,sizeof(a))
35 #define fastio ios::sync_with_stdio(false);cin.tie(0);
36 #define lson l , mid , ls
37 #define rson mid + 1 , r , rs
38 #define ls (rt<<1)
39 #define rs (ls|1)
40 #define INF 0x3f3f3f3f
41 #define LINF 0x3f3f3f3f3f3f3f3f
42 #define ll long long
43 #define ull unsigned long long
44 #define dd(x) cout << #x << " = " << (x) << ","
45 #define de(x) cout << #x << " = " << (x) << "\n"
46 #define endl "\n"
47 using namespace std;
48 //}}}
49
50 const int N=5e5+7;
51 int h[N],rh[N];
52 int cnt;
53
54 struct Node{
55     int v,next;
56 }node[N];
57 void add(int u,int v,int *h)
58 {
59     node[cnt].v=v;node[cnt].next=h[u];
60     h[u]=cnt++;
61 }
62
63 int main()
64 {
65     int n,m;cin>>n>>m;
66     int now=1;
67     cl(h,-1);cl(rh,-1);
68     rep(i,0,n){
69         string s;cin>>s;
70         int a,b,c;
71         if(s=="learn")cin>>a>>b,add(a,b,h);
72         else if(s=="rollback")cin>>c,add(c,node[h[c]].v,rh),h[c]=node[h[c]].next;
73         else if(s=="relearn")cin>>c,add(c,node[rh[c]].v,h),rh[c]=node[rh[c]].next;
74         else if(s=="clone")cin>>c,h[++now]=h[c],rh[now]=rh[c];
75         else {cin>>c;if(h[c]==-1)puts("basic");else cout<<node[h[c]].v<<endl;}
76 //        de(node[h[1]].v);
77     }
78     return 0;
79 }