public static void main ( String args [ ] ) {
  Scanner s = new Scanner ( System . in ) ;
  int n = s . nextInt ( ) ;
  String str = s . next ( ) ;
  int b = 0 , w = 0 ;
  ArrayList < Integer > black = new ArrayList < > ( ) ;
  ArrayList < Integer > white = new ArrayList < > ( ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    if ( str . charAt ( i ) == 'B' ) {
      b ++ ;
      black . add ( i + 1 ) ;
    }
    else {
      w ++ ;
      white . add ( i + 1 ) ;
    }
  }
  if ( b % 2 == 1 && w % 2 == 1 ) {
    System . out . println ( - 1 ) ;
    return ;
  }
  ArrayList < Integer > ans = new ArrayList < > ( ) ;
  if ( b % 2 == 1 ) {
    for ( int i = 1 ;
    i < white . size ( ) ;
    i = i + 2 ) {
      for ( int start = white . get ( i ) - 1 ;
      start >= white . get ( i - 1 ) ;
      start -- ) {
        ans . add ( start ) ;
      }
    }
  }
  else {
    for ( int i = 1 ;
    i < black . size ( ) ;
    i = i + 2 ) {
      for ( int start = black . get ( i ) - 1 ;
      start >= black . get ( i - 1 ) ;
      start -- ) {
        ans . add ( start ) ;
      }
    }
  }
  System . out . println ( ans . size ( ) ) ;
  for ( int num : ans ) {
    System . out . print ( num + " " ) ;
  }
}

public static void main ( String args [ ] ) { Scanner s = new Scanner ( System . in ) ; int n = s . nextInt ( ) ; String str = s . next ( ) ; int b = 0 , w = 0 ; ArrayList < Integer > black = new ArrayList < > ( ) ; ArrayList < Integer > white = new ArrayList < > ( ) ; for ( int i = 0 ; i < n ; i ++ ) { if ( str . charAt ( i ) == ' B ' ) { b ++ ; black . add ( i + 1 ) ; } else { w ++ ; white . add ( i + 1 ) ; } } if ( b % 2 == 1 && w % 2 == 1 ) { System . out . println ( - 1 ) ; return ; } ArrayList < Integer > ans = new ArrayList < > ( ) ; if ( b % 2 == 1 ) { for ( int i = 1 ; i < white . size ( ) ; i = i + 2 ) { for ( int start = white . get ( i ) - 1 ; start >= white . get ( i - 1 ) ; start -- ) { ans . add ( start ) ; } } } else { for ( int i = 1 ; i < black . size ( ) ; i = i + 2 ) { for ( int start = black . get ( i ) - 1 ; start >= black . get ( i - 1 ) ; start -- ) { ans . add ( start ) ; } } } System . out . println ( ans . size ( ) ) ; for ( int num : ans ) { System . out . print ( num + " ▁ " ) ; } }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (type_identifier) name: (identifier) dimensions: (dimensions))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments)) arguments: (argument_list)))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments)) arguments: (argument_list)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (character_literal))) consequence: (block (expression_statement (update_expression (identifier))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal)))))) alternative: (block (expression_statement (update_expression (identifier))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))))))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (decimal_integer_literal)) right: (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (decimal_integer_literal)))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (unary_expression operand: (decimal_integer_literal))))) (return_statement))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments)) arguments: (argument_list)))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (decimal_integer_literal))) consequence: (block (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) update: (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal))) body: (block (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (decimal_integer_literal)))) condition: (binary_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))) update: (update_expression (identifier)) body: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))))))) alternative: (block (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) update: (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal))) body: (block (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (decimal_integer_literal)))) condition: (binary_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))) update: (update_expression (identifier)) body: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))))) (enhanced_for_statement type: (integral_type) name: (identifier) value: (identifier) body: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (string_literal)))))))))