#include <bits/stdc++.h>
using namespace std;
#define pb push_back
const int L=21,MX=(int)(1e6+7);
int up[MX][L],d[L],idx;
char car[MX];
vector<int> vec[MX];
void Init() {
}
void TypeLetter(char L) {
vec[idx].pb(idx+1);
d[idx+1]=d[idx]+1;
up[idx+1][0]=idx;
for (int i = 1; i < L; ++i)
up[idx+1][i]=up[up[idx+1][i-1]][i-1];
car[idx+1]=L;
idx++;
}
void UndoCommands(int U) {
vec[up[idx-U][0]].pb(idx+1);
d[idx+1]=d[up[idx-U][0]]+1;
up[idx+1][0]=up[idx-U][0];
for (int i = 1; i < L; ++i)
up[idx+1][i]=up[up[idx+1][i-1]][i-1];
car[idx+1]=car[idx-U];
idx++;
}
char GetLetter(int P) {
assert((d[idx]-1)>=P);
//cerr<<P<<","<<d[idx]<<"\n";
int k=d[idx]-1-P,a=idx;
for (int i = 0; i < L; ++i)
if((k>>i)&1)a=up[a][i];
return car[a];
}
