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#include <cstdio>
int getint() {
	int r = 0; char c = getchar();
	for (; c < '0' || c > '9'; c = getchar());
	for (; '0' <= c && c <= '9'; c = getchar()) r = r * 10 - '0' + c;
	return r;
}
int getletter() {
	char c = getchar();
	for (; c < 'a' || c > 'z'; c = getchar());
	return c;
}
int getop() {
	char c = getchar();
	for (; c < 'A' || c > 'Z'; c = getchar());
	return c;
}
const int maxn = 100005;
int root[maxn], cnt, len[maxn], lc[maxn * 40], rc[maxn * 40];
char node[maxn * 40];
void update(int &x, int y, int l, int r, int pos, char d) {
	x = ++cnt;
	lc[x] = lc[y];
	rc[x] = rc[y];
	node[x] = node[y];
	if (l == r) {
		node[x] = d;
		return;
	}
	int mid = (l + r) >> 1;
	if (pos <= mid) update(lc[x], lc[y], l, mid, pos, d);
	else update(rc[x], rc[y], mid+1, r, pos, d);
}
void build(int now, int l, int r) {
	node[now] = 0;
	if (l == r) return;
	int mid = (l + r) >> 1;
	lc[now] = ++cnt;
	build(lc[now], l, mid);
	rc[now] = ++cnt;
	build(rc[now], mid+1, r);
}
char query(int x, int l, int r, int pos) {
	if (l == r) return node[x];
	int mid = (l + r) >> 1;
	if (pos <= mid) return query(lc[x], l, mid, pos);
	else return query(rc[x], mid+1, r, pos);
}
int n;
int main() {
	n = getint(); len[0] = 0;
	root[0] = ++cnt;
	build(root[0], 1, 100000);
	int czs = 0, x; char op, tmp;
	for (int i = 0; i < n; ++i) {
		op = getop();
		if (op == 'Q') {
			x = getint();
			printf("%c\n", query(root[czs], 1, 100000, x));
		} else if (op == 'U') {
			x = getint();
			++czs;
			root[czs] = root[czs - x - 1];
			len[czs] = len[czs - x - 1];
		} else {
			tmp = getletter();
			++czs;
			len[czs] = len[czs - 1] + 1;
			update(root[czs], root[czs - 1], 1, 100000, len[czs], tmp);
		}
	}
}