#include<deque>
#include<queue>
#include<vector>
#include<algorithm>
#include<iostream>
#include<set>
#include<cmath>
#include<tuple>
#include<string>
#include<chrono>
#include<functional>
#include<iterator>
#include<random>
#include<unordered_set>
#include<array>
#include<map>
#include<iomanip>
#include<assert.h>
#include<bitset>
#include<stack>
using namespace std;
typedef long long int llint;
typedef long double lldo;
#define mp make_pair
#define mt make_tuple
#define pub push_back
#define puf push_front
#define pob pop_back
#define pof pop_front
#define fir first
#define sec second
#define res resize
#define ins insert
#define era erase
/*
cout<<setprecision(20);
cin.tie(0);
ios::sync_with_stdio(false);
*/
const llint mod=998244353;
const llint big=2.19e15+1;
const long double pai=3.141592653589793238462643383279502884197;
const long double eps=1e-15;
template <class T,class U>bool mineq(T& a,U b){if(a>b){a=b;return true;}return false;}
template <class T,class U>bool maxeq(T& a,U b){if(a<b){a=b;return true;}return false;}
llint gcd(llint a,llint b){if(a%b==0){return b;}else return gcd(b,a%b);}
llint lcm(llint a,llint b){if(a==0){return b;}return a/gcd(a,b)*b;}
template<class T> void SO(T& ve){sort(ve.begin(),ve.end());}
template<class T> void REV(T& ve){reverse(ve.begin(),ve.end());}
template<class T>llint LBI(vector<T>&ar,T in){return lower_bound(ar.begin(),ar.end(),in)-ar.begin();}
template<class T>llint UBI(vector<T>&ar,T in){return upper_bound(ar.begin(),ar.end(),in)-ar.begin();}
int que=0;
int fuka[1000002];
char mozi[1000002];
array<int,20>mae[1000002];
//#include"grader.cpp"
void Init(void){
fuka[que]=0;
mozi[que]='#';
for(int h=0;h<20;h++){mae[que][h]=0;}
que++;
}
void TypeLetter(char L){
fuka[que]=(fuka[que-1]+1);
mozi[que]=L;
int gen=que-1;
for(int h=0;h<20;h++){
mae[que][h]=gen;
gen=mae[gen][h];
}
que++;
}
void UndoCommands(int U){
int bas=que-U-1;
fuka[que]=fuka[bas];
mozi[que]=mozi[bas];
mae[que]=mae[bas];
que++;
}
char GetLetter(int P){
int M=fuka[que-1]-P-1;
int gen=que-1;
for(int h=0;h<20;h++){if(M&(1<<h)){gen=mae[gen][h];}}
return mozi[gen];
}
