[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
*/