public static void main ( String [ ] args ) throws IOException {
  Scanner sc = new Scanner ( System . in ) ;
  int t = sc . nextInt ( ) ;
  while ( t -- > 0 ) {
    int robots = sc . nextInt ( ) ;
    TreeSet < Integer > xpoints = new TreeSet < > ( ) ;
    TreeSet < Integer > ypoints = new TreeSet < > ( ) ;
    HashMap < Integer , HashSet < Integer >> map = new HashMap < > ( ) ;
    for ( int i = 0 ;
    i < robots ;
    i ++ ) {
      int x = sc . nextInt ( ) ;
      int y = sc . nextInt ( ) ;
      if ( map . containsKey ( x ) ) {
        map . get ( x ) . add ( y ) ;
      }
      else {
        HashSet < Integer > temp = new HashSet < > ( ) ;
        temp . add ( y ) ;
        map . put ( x , temp ) ;
      }
      xpoints . add ( x ) ;
      ypoints . add ( y ) ;
    }
    int count = 0 ;
    int max_x = 0 ;
    int max_y = 0 ;
    String direction = "" ;
    for ( int y : ypoints ) {
      for ( int x : xpoints ) {
        if ( map . containsKey ( x ) && map . get ( x ) . contains ( y ) && max_x <= x && max_y <= y ) {
          count ++ ;
          int i = x - max_x ;
          int j = y - max_y ;
          while ( i > 0 ) {
            direction += "R" ;
            i -- ;
          }
          while ( j > 0 ) {
            direction += "U" ;
            j -- ;
          }
          max_x = x ;
          max_y = y ;
        }
      }
    }
    if ( count == robots ) {
      System . out . println ( "YES" ) ;
      System . out . println ( direction ) ;
    }
    else {
      System . out . println ( "NO" ) ;
    }
  }
}

public static void main ( String [ ] args ) throws IOException { Scanner sc = new Scanner ( System . in ) ; int t = sc . nextInt ( ) ; while ( t -- > 0 ) { int robots = sc . nextInt ( ) ; TreeSet < Integer > xpoints = new TreeSet < > ( ) ; TreeSet < Integer > ypoints = new TreeSet < > ( ) ; HashMap < Integer , HashSet < Integer > > map = new HashMap < > ( ) ; for ( int i = 0 ; i < robots ; i ++ ) { int x = sc . nextInt ( ) ; int y = sc . nextInt ( ) ; if ( map . containsKey ( x ) ) { map . get ( x ) . add ( y ) ; } else { HashSet < Integer > temp = new HashSet < > ( ) ; temp . add ( y ) ; map . put ( x , temp ) ; } xpoints . add ( x ) ; ypoints . add ( y ) ; } int count = 0 ; int max_x = 0 ; int max_y = 0 ; String direction = " " ; for ( int y : ypoints ) { for ( int x : xpoints ) { if ( map . containsKey ( x ) && map . get ( x ) . contains ( y ) && max_x <= x && max_y <= y ) { count ++ ; int i = x - max_x ; int j = y - max_y ; while ( i > 0 ) { direction += " R " ; i -- ; } while ( j > 0 ) { direction += " U " ; j -- ; } max_x = x ; max_y = y ; } } } if ( count == robots ) { System . out . println ( " YES " ) ; System . out . println ( direction ) ; } else { System . out . println ( " NO " ) ; } } }
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(argument_list (identifier)))) right: (binary_expression left: (identifier) right: (identifier))) right: (binary_expression left: (identifier) right: (identifier)))) consequence: (block (expression_statement (update_expression (identifier))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (identifier)))) (while_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) body: (block (expression_statement (assignment_expression left: (identifier) right: (string_literal))) (expression_statement (update_expression (identifier))))) (while_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) body: (block (expression_statement (assignment_expression left: (identifier) right: (string_literal))) (expression_statement (update_expression (identifier))))) (expression_statement (assignment_expression left: (identifier) right: (identifier))) (expression_statement (assignment_expression left: (identifier) right: (identifier))))))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list 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