// ~ Be Name Khoda ~ //
#include <bits/stdc++.h>
//#pragma GCC optimize ("O3")
//#pragma GCC target("avx2")
//#pragma GCC optimize("unroll-loops,Ofast")
using namespace std;
typedef long long ll;
#define pb push_back
#define mp make_pair
#define all(x) x.begin(), x.end()
#define fi first
#define se second
const int maxn = 1e6 + 10;
const int maxn5 = 1e6 + 10;
const int maxnt = 1.2e6 + 10;
const int maxn3 = 1e3 + 10;
const int mod = 1e9 + 7;
const int lg = 20;
const ll inf = 1e18;
int cur, newnode = 1, pt = 0, st[maxn5];
int par[lg][maxn5], h[maxn5];
char op[maxn5], parchar[maxn5];
void Init(){
cur = 0;
memset(par, -1, sizeof par);
h[0] = 0;
}
void TypeLetter(char l){
//cout << "ok we are in " << l << ' ' << cur << ' ' << endl;
op[pt] = l;
int v = newnode++;
par[0][v] = cur;
h[v] = h[cur] + 1;
for(int i = 1; i < lg && par[i - 1][v] != -1; i++)
par[i][v] = par[i - 1][par[i - 1][v]];
parchar[v] = l;
cur = v;
st[pt++] = cur;
//cout << "now in " << cur << endl;
}
void UndoCommands(int t){
//cout << "undo from " << cur << endl;
op[pt++] = 'U';
cur = st[pt - t - 2];
st[pt - 1] = cur;
//cout << "to " << t << ' ' << cur << ' ' << st[0] << endl;
}
char GetLetter(int pos){
//cout << "while in " << cur << ' ' << pos << ' ' << h[cur] << endl;
int d = h[cur] - pos - 1;
int v = cur;
for(int i = 0; i < lg; i++) if((d >> i)&1)
v = par[i][v];
return parchar[v];
}
/*
6
T a
T b
T d
U 2
U 1
P 2
*/
