/**************************************************************Problem: 3123User: BLADEVILLanguage: C++Result: AcceptedTime:16612 msMemory:81512 kb
****************************************************************///By BLADEVIL
#include <cstdio>
#include <cstring>
#include <algorithm>
#define maxn 100010
#define maxm 200010using namespace std;struct rec {int key,num;rec() {key=num=0;}
}a[maxn];struct segment {int left,right,cnt;int son[2];segment() {left=right=cnt=0;memset(son,0,sizeof son);}
}t[maxn<<5];int n,m,l,N,tot;
int pre[maxm<<1],last[maxm<<1],other[maxm<<1];
int ans[maxn],rot[maxn];
int dep[maxn],jump[maxn][20],father[maxn],size[maxn],que[maxn];void connect(int x,int y) {pre[++l]=last[x];last[x]=l;other[l]=y;
}int getfather(int x) {if (father[x]==x) return x;return father[x]=getfather(father[x]);
}void dfs(int x,int fa) {jump[x][0]=fa; dep[x]=dep[fa]+1;for (int p=last[x];p;p=pre[p]) {if (other[p]==fa) continue;dfs(other[p],x);}
}bool cmp1(rec x,rec y) {return x.key<y.key;
}bool cmp2(rec x,rec y) {return x.num<y.num;
}int lca(int x,int y) {if (dep[x]>dep[y]) swap(x,y);int d=dep[y]-dep[x];for (int i=0;i<=16;i++) if (d&(1<<i)) y=jump[y][i];if (x==y) return x;for (int i=16;i>=0;i--) if (jump[x][i]!=jump[y][i]) x=jump[x][i],y=jump[y][i];return jump[x][0];
}void build(int &x,int l,int r) {if (!x) x=++tot;t[x].left=l; t[x].right=r;if (t[x].left==t[x].right) return ;int mid=t[x].left+t[x].right>>1;build(t[x].son[0],l,mid); build(t[x].son[1],mid+1,r);
}void insert(int &x,int rot,int key) {if (!x) x=++tot;t[x].left=t[rot].left; t[x].right=t[rot].right;if (t[x].left==t[x].right) {t[x].cnt=t[rot].cnt+1;return ;}int mid=t[x].left+t[x].right>>1;if (key>mid) {t[x].son[0]=t[rot].son[0];insert(t[x].son[1],t[rot].son[1],key);} else {t[x].son[1]=t[rot].son[1];insert(t[x].son[0],t[rot].son[0],key);}t[x].cnt=t[rot].cnt+1;
}int query(int x,int y,int l1,int l2,int k) {//printf("%d %d %d ",x,t[x].left,t[x].right);if (t[x].left==t[x].right) return t[x].left;int cur=t[t[x].son[0]].cnt+t[t[y].son[0]].cnt-t[t[l1].son[0]].cnt-t[t[l2].son[0]].cnt;//printf("%d\n",cur);if (k>cur) return query(t[x].son[1],t[y].son[1],t[l1].son[1],t[l2].son[1],k-cur); elsereturn query(t[x].son[0],t[y].son[0],t[l1].son[0],t[l2].son[0],k);
}void make(int x,int fa) {insert(rot[x],rot[fa],a[x].key);for (int p=last[x];p;p=pre[p]) {if (other[p]==fa) continue;make(other[p],x);}
}void update(int x,int fa,int j) {jump[x][j]=jump[jump[x][j-1]][j-1];for (int p=last[x];p;p=pre[p]) {if (other[p]==fa) continue;update(other[p],x,j);}
}void merge(int x,int y) {int fx=getfather(x),fy=getfather(y);//if (x==1) printf("%d %d\n",fx,fy);if (size[fx]<size[fy]) swap(x,y);fx=getfather(x),fy=getfather(y);father[fy]=fx; size[fx]+=size[fy];dfs(y,x); make(y,x); for (int i=1;i<=16;i++) update(y,x,i);//for (int i=1;i<=n;i++) printf("%d %d\n",i,jump[i][0]);
}int main() {//freopen("3123.in","r",stdin); freopen("3123.out","w",stdout);int task; scanf("%d",&task);scanf("%d%d%d",&n,&m,&task);for (int i=1;i<=n;i++) scanf("%d",&a[a[i].num=i].key); sort(a+1,a+1+n,cmp1);int cur; ans[1]=cur=a[1].key;for (int i=1,j=1;i<=n;i++) if (a[i].key==cur) a[i].key=j; else ans[++j]=cur=a[i].key,a[i].key=j,N=j;sort(a+1,a+1+n,cmp2);//for (int i=1;i<=n;i++) printf("%d ",ans[i]); printf("\n");//for (int i=1;i<=n;i++) printf("%d ",a[i].key); printf("\n");for (int i=1;i<=n;i++) father[i]=i,size[i]=1;for (int i=1;i<=m;i++) {int x,y; scanf("%d%d",&x,&y);connect(x,y); connect(y,x);int fx=getfather(x),fy=getfather(y);father[fx]=fy; size[fy]+=size[fx];}for (int i=1;i<=n;i++) if (!jump[i][0]) dfs(i,0);//for (int i=1;i<=n;i++) printf("%d %d\n",i,father[i]);//for (int i=1;i<=n;i++) if (i==getfather(i)) printf("%d %d\n",i,size[i]);for (int j=1;j<=16;j++)for (int i=1;i<=n;i++) jump[i][j]=jump[jump[i][j-1]][j-1];build(rot[0],1,N);for (int i=1;i<=n;i++) if (!jump[i][0]) make(i,0);int ANS=0; char Q[3];while (task--) {scanf("%s",Q);if (Q[0]=='Q') {int x,y,k; scanf("%d%d%d",&x,&y,&k);x^=ANS; y^=ANS; k^=ANS;//printf("|%d %d %d\n",x,y,k);int rr=lca(x,y); //printf("%d\n",rr);//for (int i=1;i<=n;i++) printf("%d %d\n",i,jump[i][0]);printf("%d\n",ANS=ans[query(rot[x],rot[y],rot[rr],rot[jump[rr][0]],k)]);//for (int i=1;i<=n;i++) if (i==getfather(i)) printf("%d %d\n",i,size[i]);} else {    int x,y; scanf("%d%d",&x,&y);x^=ANS; y^=ANS; connect(x,y); connect(y,x);//printf("|%d %d\n",x,y);
            merge(x,y);}}return 0;
}