import java.lang.*;
import java.math.*;
import java.util.*;
import java.io.*;
public class Main {
    void solve() {
        int t=ni();
        while(t-->0){
            int n=ni();
            g=new ArrayList[n+1];
            for(int i=1;i<=n;i++) g[i]=new ArrayList<>();
            for(int i=1;i<n;i++){
                int u=ni(),v=ni();
                g[u].add(v); g[v].add(u);
            }
            in1=new boolean[n+1];
            in2=new boolean[n+1];

            int k1=ni();
            for(int i=1;i<=k1;i++)in1[ni()]=true;
            int id=-1;
            int k2=ni();
            for(int i=1;i<=k2;i++){
                id=ni();
                in2[id]=true;
            }
            ans=-1;
            id=ask('B',id);
            dfs(id,-1);
            if(in2[ask('A',ans)]){
                System.out.println("C "+ans);
            }else {
                System.out.println("C -1");
            }
            System.out.flush();

        }
    }
    ArrayList<Integer> g[];
    boolean in1[],in2[];
    int ans;
    boolean dfs(int v,int pr){
        if(in1[v]) {
            ans=v;
            return true;
        }
        for(int u : g[v]){
            if(u!=pr){
                if(dfs(u,v)) return true;
            }
        }
        return false;
    }
    int ask(char ch ,int idx){
        System.out.println(ch+" "+idx);
        System.out.flush();
        return ni();
    }

    long M =(long)1e9+7;
    InputStream is;
    PrintWriter pw;
    String INPUT = "";

    void run() throws Exception {
        is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
        pw = new PrintWriter(System.out);
        long s = System.currentTimeMillis();
        solve();
        pw.flush();
        if (!INPUT.isEmpty()) tr(System.currentTimeMillis() - s + "ms");


    }

    public static void main(String[] args) throws Exception {
        new Main().run();
    }

    private byte[] inbuf = new byte[1024];
    public int lenbuf = 0, ptrbuf = 0;

    private int readByte() {
        if (lenbuf == -1) throw new InputMismatchException();
        if (ptrbuf >= lenbuf) {
            ptrbuf = 0;
            try {
                lenbuf = is.read(inbuf);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
            if (lenbuf <= 0) return -1;
        }
        return inbuf[ptrbuf++];
    }

    private boolean isSpaceChar(int c) {
        return !(c >= 33 && c <= 126);
    }

    private int skip() {
        int b;
        while ((b = readByte()) != -1 && isSpaceChar(b)) ;
        return b;
    }

    private double nd() {
        return Double.parseDouble(ns());
    }

    private char nc() {
        return (char) skip();
    }

    private String ns() {
        int b = skip();
        StringBuilder sb = new StringBuilder();
        while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    private char[] ns(int n) {
        char[] buf = new char[n];
        int b = skip(), p = 0;
        while (p < n && !(isSpaceChar(b))) {
            buf[p++] = (char) b;
            b = readByte();
        }
        return n == p ? buf : Arrays.copyOf(buf, p);
    }

    private char[][] nm(int n, int m) {
        char[][] map = new char[n][];
        for (int i = 0; i < n; i++) map[i] = ns(m);
        return map;
    }

    private int[] na(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++) a[i] = ni();
        return a;
    }

    private int ni() {
        int num = 0, b;
        boolean minus = false;
        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')) ;
        if (b == '-') {
            minus = true;
            b = readByte();
        }

        while (true) {
            if (b >= '0' && b <= '9') {
                num = num * 10 + (b - '0');
            } else {
                return minus ? -num : num;
            }
            b = readByte();
        }
    }

    private long nl() {
        long num = 0;
        int b;
        boolean minus = false;
        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')) ;
        if (b == '-') {
            minus = true;
            b = readByte();
        }

        while (true) {
            if (b >= '0' && b <= '9') {
                num = num * 10 + (b - '0');
            } else {
                return minus ? -num : num;
            }
            b = readByte();
        }
    }

    private boolean oj = System.getProperty("ONLINE_JUDGE") != null;

    private void tr(Object... o) {
        if (INPUT.length() > 0) System.out.println(Arrays.deepToString(o));
    }

}