# include <bits/stdc++.h>
using namespace std;
char last;
vector <char> t;
vector <int> pos;
vector <int> par;
stack <char> st;
bool fl = false;
int prevv=-1, ver=-1;
vector <char> w;
void Init() {
prevv = -1;
ver = -1;
t.clear();
pos.clear();
par.clear();
//st.clear();
fl = false;
}
void TypeLetter(char L) {
last = L;
ver++;
pos.push_back(ver);
t.push_back(L);
par.push_back(prevv);
prevv = ver;
}
void UndoCommands(int U) {
int k = pos[pos.size()-U-1];
pos.push_back(k);
prevv = k;
}
char GetLetter(int P) {
if(!fl)
{
for(int i = prevv; i!=-1; i =par[i])
{
st.push(t[i]);
}
while(!st.empty())
{
w.push_back(st.top());
st.pop();
}
fl= true;
}
return w[P];
//return last;
}
