/*
Author of all code: Pedro BIGMAN Dias
Last edit: 15/02/2021
*/
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#pragma GCC optimize("Ofast")
#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <string>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <queue>
#include <deque>
#include <list>
#include <iomanip>
#include <stdlib.h>
#include <time.h>
#include <cstring>
using namespace std;
typedef int ll;
typedef unsigned long long int ull;
typedef long double ld;
#define REP(i,a,b) for(ll i=(ll) a; i<(ll) b; i++)
#define pb push_back
#define mp make_pair
#define pl pair<ll,ll>
#define ff first
#define ss second
#define whole(x) x.begin(),x.end()
#define DEBUG(i) cout<<"Pedro Is The Master "<<i<<endl
#define INF 1000000000000000000LL
#define EPS ((ld)0.00000000001)
#define pi ((ld)3.141592653589793)
#define VV(vvvv,NNNN,xxxx); REP(iiiii,0,NNNN) {vvvv.pb(xxxx);}
ll mod=1000000007LL;
template<class A=ll>
void Out(vector<A> a) {REP(i,0,a.size()) {cout<<a[i]<<" ";} cout<<endl;}
template<class A=ll>
void In(vector<A> &a, ll N) {A cur; REP(i,0,N) {cin>>cur; a.pb(cur);}}
vector<ll> S;
vector<pl> s;
vector<vector<pl> > f; //f2[i][exp] = {node after 2^exp moves, number of letters}
void Init()
{
return;
}
void AddState(ll val, ll nxt)
{
s.pb({val,nxt});
if(S.size()>nxt) {S.pb(S[nxt]+min(val+1,1));} else {S.pb(1);}
ll exp=0; ll curval = min(s[nxt].ff+1,1); if(s.size()==1) {curval=0;} ll ind = s.size()-1;
f.pb({}); f[ind].pb({nxt,curval}); ll curind = nxt; ll inc;
while(1>0)
{
if(curind==0) {break;}
nxt = f[curind][min(exp,(int)f[curind].size()-1)].ff; ll inc = f[curind][min(exp,(int)f[curind].size()-1)].ss;
f[ind].pb({nxt,curval+inc});
curind=nxt; curval+=inc; exp++;
}
}
void TypeLetter(char L)
{
ll val = (ll) (L-'a');
AddState(val,max(0,(int)(s.size()-1)));
}
void UndoCommands(int U)
{
AddState(-1,s.size()-1-U);
}
char GetLetter(int P)
{
ll needed = S.back()-P;
ll curind=s.size()-1; ll curval = min(1,s[curind].ff+1);
ll exp = (ll) log2(s.size()); ll poss; ll nxt;
ll ans=s[curind].ff;
while(curval<needed)
{
poss=curval+f[curind][min(exp,(int)f[curind].size()-1)].ss;
if(poss<needed) {curval+=poss; curind = f[curind][min(exp,(int)f[curind].size()-1)].ff; exp--; continue;}
if(poss>needed) {exp--; continue;}
nxt = f[curind][min(exp,(int)f[curind].size()-1)].ff; if(s[nxt].ff>=0) {ans = s[nxt].ff; break;} exp--;
}
return ((char) ans+'a');
}
