本地还是可以跑的，但是放到洛谷IDE上面就RE了

#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
const int MAXN=2e5+5;
int key[MAXN],fa[MAXN];
inline int find(int x)
{
	if(x==fa[x])return fa[x];
	return fa[x]=find(fa[x]);
}
inline void merge(int x,int y)
{
	int fx=find(x),fy=find(y);
	fa[fx]=fy;
}
int n,m,q;
tree<int,int,greater<int>,rb_tree_tag,tree_order_statistics_node_update>t[MAXN];
inline void merge_tree(int x,int y)
{
	x=fa[x],y=fa[y];
	if(x==y)return;
	if(t[x].size()>t[y].size())swap(x,y);
	for(tree<int,int,greater<int>,rb_tree_tag,tree_order_statistics_node_update>::point_iterator it=t[x].begin();it!=t[x].end();it++)
	{
		t[y].insert(make_pair(it->first,it->second));
		t[x].erase(it);
	}
	merge(x,y);
}
int main()
{
	scanf("%d%d",&n,&m);
	for(register int i=1;i<=n;i++)
		fa[i]=i;
	for(register int i=1;i<=n;i++)
		scanf("%d",&key[i]);
	for(register int i=1;i<=m;i++)
	{
		int x,y;
		scanf("%d%d",&x,&y);
		merge(x,y);
	}
	for(register int i=1;i<=n;i++)
		t[find(i)].insert(make_pair(key[i],i));
	scanf("%d",&q);
	for(register int i=1;i<=q;i++)
	{
		char op[5];
		int x,y;
		scanf("%s",op);
        scanf("%d%d",&x,&y);
		if(op[0]=='B')merge_tree(x,y);
		if(op[0]=='Q')
		{
			x=find(x);
			cout<<x<<endl;
			if(y>int(t[x].size()))puts("-1");
			else printf("%d\n",t[x].find_by_order(t[x].size()-y)->second);
		}
	}
	return 0;
}