[SDOI2013]森林 (启发式合并)

/*

树上主席树能够求出链上第k大， 然后启发式合并直接重构就好了

卡常数就卡呗

反正我就暴力重构了！！

*/

#include<cstdio>

#include<algorithm>

#include<cstring>

#include<queue>

#include<iostream>

#define ll long long

#define mmp make_pair

#define M 100010

using namespace std;

int read() {

	int nm = 0, f = 1;

	char c = getchar();

	for(; !isdigit(c); c = getchar()) if(c == '-') f = -1;

	for(; isdigit(c); c = getchar()) nm = nm * 10 + c - '0';

	return nm * f;

}

int fa[M][17], sz[M], rt[M], belong[M], n, m, T, cnt, a[M], b[M], deep[M], ans;

int t[M * 17 * 17], ls[M * 17 * 17], rs[M * 17 * 17];

vector<int> to[M];

char s[M];

void modify(int l, int r, int last, int &now, int v) {

	now = ++cnt;

	t[now] = t[last] + 1;

	ls[now] = ls[last];

	rs[now] = rs[last];

	if(l == r) return;

	int mid = (l + r) >> 1;

	if(v <= mid) modify(l, mid, ls[last], ls[now], v);

	else modify(mid + 1, r, rs[last], rs[now], v);

}

void dfs(int now, int f, int zu) {

	belong[now] = zu;

	deep[now] = deep[f] + 1;

	modify(1, n, rt[f], rt[now], a[now]);

	fa[now][0] = f;

	for(int i = 1; i <= 16; i++) fa[now][i] = fa[fa[now][i - 1]][i - 1];

	for(int i = 0; i < to[now].size(); i++) {

		int vj = to[now][i];

		if(vj == f) continue;

		dfs(vj, now, zu);

	}

}

int lca(int a, int b) {

	if(deep[a] < deep[b]) swap(a, b);

	int dep = deep[a] - deep[b];

	for(int i = 0; dep; i++, dep >>= 1) if(dep & 1) a = fa[a][i];

	if(a == b) return a;

	for(int i = 16; i >= 0; i--) {

		if(fa[a][i] == fa[b][i]) continue;

		a = fa[a][i], b = fa[b][i];

	}

	return fa[a][0];

}

int query(int l, int r, int rt1, int rt2, int rt3, int rt4, int k) {

	if(l == r) return l;

	int mid = (l + r) >> 1;

	int v = t[ls[rt4]] + t[ls[rt3]] - t[ls[rt2]] - t[ls[rt1]];

	if(k <= v) return query(l, mid, ls[rt1], ls[rt2], ls[rt3], ls[rt4], k);

	else return query(mid + 1, r, rs[rt1], rs[rt2], rs[rt3], rs[rt4], k - v);

}

int main() {

	read();

	n = read(), m = read(), T = read();

	for(int i = 1; i <= n; i++) a[i] = b[i] = read();

	sort(b + 1, b + n + 1);

	for(int i = 1; i <= n; i++) a[i] = lower_bound(b + 1, b + n + 1, a[i]) - b;

	for(int i = 1; i <= m; i++) {

		int vi = read(), vj = read();

		to[vi].push_back(vj);

		to[vj].push_back(vi);

	}

	for(int i = 1; i <= n; i++) {

		if(!belong[i]) dfs(i, 0, i);

	}

	for(int i = 1; i <= n; i++) sz[belong[i]]++;

	while(T--) {

		scanf("%s", s + 1);

		if(s[1] == 'Q') {

			int vi = read() ^ ans, vj = read() ^ ans, k = read() ^ ans;

			int l = lca(vi, vj);

			ans = b[query(1, n, rt[l], rt[fa[l][0]], rt[vi], rt[vj], k)];

			cout << ans << "\n";

		} else {

			int vi = read() ^ ans, vj = read() ^ ans;

			if(sz[belong[vi]] > sz[belong[vj]]) swap(vi, vj);

			sz[belong[vj]] += sz[belong[vi]];

			sz[belong[vi]] = 0;

			dfs(vi, vj, belong[vj]);

			to[vi].push_back(vj);

			to[vj].push_back(vi);

		}

	}

	return 0;

}

/*

10

5 0 5

1 2 3 4 5

L 1 2

L 2 3

L 1 5

L 4 5

Q 3 4 1

*/