#include "bits/extc++.h"
using namespace std;
template <typename T>
void dbgh(const T& t) {
cerr << t << endl;
}
template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
cerr << t << " | ";
dbgh(u...);
}
#ifdef DEBUG
#define dbg(...) \
cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]: "; \
dbgh(__VA_ARGS__);
#else
#define dbg(...)
#define cerr \
if (false) \
cerr
#endif
#define endl "\n"
#define long int64_t
#define sz(x) int((x).size())
struct Node {
int siz, lc, rc;
int gsize() {
if (siz < 0) {
return 1;
}
return siz;
}
} heap[(250 << 20) / sizeof(Node)];
int hind = 1;
void push(int& o, int l, int r, int x) {
heap[hind] = heap[o];
o = hind++;
auto &[siz, lc, rc] = heap[o];
if (l == r) {
dbg(l, x);
siz = -x;
} else {
int mid = (l + r) / 2;
if (heap[lc].gsize() == mid - l + 1) {
push(rc, mid + 1, r, x);
} else {
push(lc, l, mid, x);
}
siz = heap[lc].gsize() + heap[rc].gsize();
}
}
int query(int o, int l, int r, int ind) {
auto& [siz, lc, rc] = heap[o];
if (l == r) {
return -siz;
} else {
int mid = (l + r) / 2;
if (ind <= mid) {
return query(lc, l, mid, ind);
} else {
return query(rc, mid + 1, r, ind);
}
}
}
vector<int> roots {hind++};
const int maxn = 1e6 + 5;
void Init() {}
void TypeLetter(char c) {
roots.push_back(roots.back());
push(roots.back(), 0, maxn, c);
}
void UndoCommands(int x) {
roots.push_back(roots[sz(roots) - x - 1]);
}
char GetLetter(int ind) {
return query(roots.back(), 0, maxn, ind);
}
