#include <bits/stdc++.h>
#define FR(i, N) for (int i = 0; i < int(N); i++)
#define all(x) begin(x), end(x)
#pragma GCC optimize ("Ofast")
#pragma GCC target ("avx2")
using namespace std;
using ll = long long;
const int MAXN = (int)(1e7) + 5;
const int MAXK = 20;
int up[MAXN][MAXK];
int undo[MAXN][MAXK];
int depth[MAXN];
char res[MAXN];
int cnt = 1;
int liftUp(int u, int d) {
for (int i = 0; i < MAXK; i++) {
if (d&(1<<i)) {
u = up[u][i];
}
}
return u;
}
int liftUndo(int u, int d) {
for (int i = 0; i < MAXK; i++) {
if (d&(1<<i)) {
u = undo[u][i];
}
}
return u;
}
void Init() {
}
void TypeLetter(char L) {
res[cnt] = L;
up[cnt][0] = cnt-1;
undo[cnt][0] = cnt-1;
for (int i = 1; i < MAXK; i++) {
up[cnt][i] = up[up[cnt][i-1]][i-1];
// undo[cnt][i] = undo[undo[cnt][i-1]][i-1];
}
depth[cnt] = depth[cnt-1]+1;
cnt++;
}
void UndoCommands(int U) {
int next = cnt-1-U;
res[cnt] = res[next];
up[cnt][0] = up[next][0];
undo[cnt][0] = cnt-1;
for (int i = 1; i < MAXK; i++) {
up[cnt][i] = up[up[cnt][i-1]][i-1];
// undo[cnt][i] = undo[undo[cnt][i-1]][i-1];
}
depth[cnt] = depth[next];
cnt++;
}
char GetLetter(int P) {
return res[liftUp(cnt-1, depth[cnt-1] - P - 1)];
}
//int main() {
// Init();
//
// int cmd_num, tmp;
// tmp = scanf("%d", &cmd_num);
//
// int i;
// for (i = 0; i < cmd_num; i++) {
// char cmd;
// int tmp = scanf(" %c", &cmd);
// if (cmd == 'T') {
// char letter;
// tmp = scanf(" %c", &letter);
// TypeLetter(letter);
// }
// else if (cmd == 'U') {
// int number;
// tmp = scanf("%d", &number);
// UndoCommands(number);
// }
// else if (cmd == 'P') {
// int index;
// char letter;
// tmp = scanf("%d", &index);
// letter = GetLetter(index);
// printf("%c\n", letter);
// }
// }
//
// puts("Let's test for cheating!!");
//
// return 0;
//
//}
