#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> ti;
typedef vector<ll> li;
typedef vector<li> lii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define LSOne(s) ((s)&(-s))
ll INF=1000000000000000010;
int inf=1e9+10;
ll M=1e9+7;
vector<char> b;
int pos=1,mx=1000010,k;
vii p;
vi arr,d;
void Init() {
k=log2(mx)+1;
p.resize(mx,vi(k,-1));
b.resize(mx);d.resize(mx);
d[0]=-1;arr.PB(0);
REP(i,0,mx)p[i][0]=i;
}
void TypeLetter(char L) {
int x=arr.back();
p[pos][0]=x;
REP(j,1,k)if(p[pos][j-1]!=-1)p[pos][j]=p[p[pos][j-1]][j-1];
b[pos]=L;
d[pos]=d[x]+1;
arr.PB(pos);
pos++;
}
void UndoCommands(int U) {
int y=arr.size();
arr.PB(arr[y-U-1]);
}
char GetLetter(int P) {
int x=arr.back();
int y=d[x];
int z=y-P;
while(z){
int t=LSOne(z);
x=p[x][log2(t)];
z-=t;
}
return b[x];
}
