public static void main ( String [ ] args ) throws IOException {
  BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  int cases = Integer . parseInt ( br . readLine ( ) ) ;
  while ( cases > 0 ) {
    int daughters = Integer . parseInt ( br . readLine ( ) ) ;
    int [ ] necklaces = Arrays . stream ( br . readLine ( ) . split ( " " ) ) . mapToInt ( x -> Integer . parseInt ( x ) ) . toArray ( ) ;
    int [ ] bracelets = Arrays . stream ( br . readLine ( ) . split ( " " ) ) . mapToInt ( x -> Integer . parseInt ( x ) ) . toArray ( ) ;
    Arrays . sort ( necklaces ) ;
    Arrays . sort ( bracelets ) ;
    for ( int i = 0 ;
    i < daughters ;
    i ++ ) {
      if ( i + 1 != daughters ) {
        System . out . print ( necklaces [ i ] + " " ) ;
      }
      else {
        System . out . println ( necklaces [ i ] ) ;
      }
    }
    for ( int i = 0 ;
    i < daughters ;
    i ++ ) {
      if ( i + 1 != daughters ) {
        System . out . print ( bracelets [ i ] + " " ) ;
      }
      else {
        System . out . println ( bracelets [ i ] ) ;
      }
    }
    cases -- ;
  }
}

public static void main ( String [ ] args ) throws IOException { BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ; int cases = Integer . parseInt ( br . readLine ( ) ) ; while ( cases > 0 ) { int daughters = Integer . parseInt ( br . readLine ( ) ) ; int [ ] necklaces = Arrays . stream ( br . readLine ( ) . split ( " ▁ " ) ) . mapToInt ( x -> Integer . parseInt ( x ) ) . toArray ( ) ; int [ ] bracelets = Arrays . stream ( br . readLine ( ) . split ( " ▁ " ) ) . mapToInt ( x -> Integer . parseInt ( x ) ) . toArray ( ) ; Arrays . sort ( necklaces ) ; Arrays . sort ( bracelets ) ; for ( int i = 0 ; i < daughters ; i ++ ) { if ( i + 1 != daughters ) { System . out . print ( necklaces [ i ] + " ▁ " ) ; } else { System . out . println ( necklaces [ i ] ) ; } } for ( int i = 0 ; i < daughters ; i ++ ) { if ( i + 1 != daughters ) { System . out . print ( bracelets [ i ] + " ▁ " ) ; } else { System . out . println ( bracelets [ i ] ) ; } } cases -- ; } }
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