#include <bits/stdc++.h>
using namespace std;

namespace q_wr {
	inline int read() {
		char c = getchar();
		int x = 0, f = 1;
		while (c < '0' || c > '9') {
			if (c == '-') f = -1;
			c = getchar();
		}
		while (c >= '0' && c <= '9') {
			x = (x << 1) + (x << 3) + c - '0';
			c = getchar();
		}
		return x * f;
	}
	inline void write(int x) {
		if (x < 0) {
			x = ~(x - 1);
			putchar('-');
		}
		if (x > 9)
			write(x / 10);
		putchar(x % 10 + '0');
	}
}

using namespace q_wr;

const int maxn = 1e5 + 500;

struct segtree {
	int ls, rs;
	char val;
} tr[maxn * 32];

int n, vs, rt[maxn], cnt, len[maxn];

int modify (int s, int l, int r, int p, char c) {
	int o = ++cnt;
	tr[o] = tr[p];
	if (l == r) {
		tr[o].val = c;
		return o;
	}
	int mid = (l + r) >> 1;
	if (s <= mid) tr[o].ls = modify(s, l, mid, tr[p].ls, c);
	else tr[o].rs = modify(s, mid + 1, r, tr[p].rs, c);
	return o;
}

void query (int s, int l, int r, int p) {
	if (l == r) {
		cout << tr[p].val;
		puts("");
		return;
	}
	int mid = (l + r) >> 1;
	if (s <= mid) query(s, l, mid, tr[p].ls);
	else query(s, mid + 1, r, tr[p].rs);
}

int main () {
	n = read();
	for (int i = 1; i <= n; i++) {
		char opt;
		cin >> opt;
		if (opt == 'T') {
			char c;
			cin >> c;
			len[++vs] = len[vs - 1] + 1;
//			cout << len[vs] << "\n";
			rt[vs] = modify(len[vs], 1, n, rt[vs - 1], c);
		} 
		if (opt == 'U') {
			int x = read();
			len[++vs] = len[vs - x - 1];
			rt[vs] = rt[vs - x - 1];
		}
		if (opt == 'Q') {
			int x = read();
			query(x, 1, n, rt[vs]);
		}
	}
}

WA on test #1~10