#include<bits/stdc++.h>
using namespace std ;
typedef long long ll ;
typedef unsigned long long ull ;
typedef pair < int , int > pii ;
typedef vector < int > vi ;
#define fi first
#define se second
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()

const int MAXN = 2e5 + 7 ;

int n , m ;
vector < int > v[ 2 ][ MAXN ] ;
vector < int > ord[ 2 ] ;

vector < int > gr[ MAXN ] ;

void dfs ( int x , int hh ) {
    if ( v[ hh ][ x ].empty ( ) == true ) {
        ord[ hh ].push_back ( x ) ;
    }
    for ( auto y : v[ hh ][ x ] ) {
        dfs ( y , hh ) ;
    }
}

int ans[ MAXN ] ;

void mrk ( int x , int prv , int col ) {
    ans[ x ] = col ;
    if ( prv == gr[ x ][ 0 ] ) {
        if ( ans[ gr[ x ][ 1 ] ] == 0 ) { 
            mrk ( gr[ x ][ 1 ] , x , 3 - col ) ;
        }
    }
    else {
        if ( ans[ gr[ x ][ 0 ] ] == 0 ) { 
            mrk ( gr[ x ][ 0 ] , x , 3 - col ) ;
        }
    }
}

void solve ( ) {
    cin >> n >> m ;
    for ( int i = 0 ; i <= max ( n , m ) ; ++ i ) {
        v[ 0 ][ i ].clear ( ) , v[ 1 ][ i ].clear ( ) ;
    }
    for ( int i = 1 , x ; i < n ; ++ i ) {
        cin >> x ;
        v[ 0 ][ x ].push_back ( i ) ;
    }
    for ( int i = 1 , x ; i < m ; ++ i ) {
        cin >> x ;
        v[ 1 ][ x ].push_back ( i ) ;
    }
    ord[ 0 ].clear ( ) , ord[ 1 ].clear ( ) ;
    dfs ( n , 0 ) ;
    dfs ( m , 1 ) ;

    for ( int i = 0 ; i <= max ( n , m ) ; ++ i ) {
        gr[ i ].clear ( ) ;
        ans[ i ] = 0 ;
    }
    int k = ord[ 0 ].size ( ) ;
    int ori = k ;
    if ( ( k % 2 ) == 1 ) { 
        ord[ 0 ].push_back ( 0 ) ;
        ord[ 1 ].push_back ( 0 ) ;
        ++ k ;
    }
    for ( int i = 0 ; i < k ; i += 2 ) {
        int nxt = ( i + 1 ) % k ;
        gr[ ord[ 0 ][ i ] ].push_back ( ord[ 0 ][ nxt ] ) ;
        gr[ ord[ 0 ][ nxt ] ].push_back ( ord[ 0 ][ i ] ) ;

        gr[ ord[ 1 ][ i ] ].push_back ( ord[ 1 ][ nxt ] ) ;
        gr[ ord[ 1 ][ nxt ] ].push_back ( ord[ 1 ][ i ] ) ;
    }
    for ( int i = 1 ; i <= ori ; ++ i ) {
        if ( ans[ i ] == 0 ) {
            mrk ( i , -1 , 1 ) ;
        }
    }
    for ( int i = 1 ; i <= ori ; ++ i ) {
        if ( ans[ i ] == 1 ) { cout << "B" ; }
        else { cout << "R" ; }
    }
    cout << "\n" ;
}

int main ( ) {
    ios_base :: sync_with_stdio ( false ) ;
    cin.tie ( NULL ) ;
    int t = 1 ; cin >> t ;
    while ( t -- ) { solve ( ) ; }
    return 0 ;
}