public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  String s = sc . next ( ) ;
  int r = 0 ;
  int g = 0 ;
  int b = 0 ;
  for ( char c : s . toCharArray ( ) ) {
    switch ( c ) {
      case 'R' : r ++ ;
      break ;
      case 'G' : g ++ ;
      break ;
      case 'B' : b ++ ;
      break ;
    }
  }
  System . out . println ( r % 2 + g % 2 + b % 2 ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; String s = sc . next ( ) ; int r = 0 ; int g = 0 ; int b = 0 ; for ( char c : s . toCharArray ( ) ) { switch ( c ) { case ' R ' : r ++ ; break ; case ' G ' : g ++ ; break ; case ' B ' : b ++ ; break ; } } System . out . println ( r % 2 + g % 2 + b % 2 ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) 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))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (enhanced_for_statement type: (integral_type) name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) body: (block (switch_expression condition: (parenthesized_expression (identifier)) body: (switch_block (switch_block_statement_group (switch_label (character_literal)) (expression_statement (update_expression (identifier))) (break_statement)) (switch_block_statement_group (switch_label (character_literal)) (expression_statement (update_expression (identifier))) (break_statement)) (switch_block_statement_group (switch_label (character_literal)) (expression_statement (update_expression (identifier))) (break_statement)))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (binary_expression left: (identifier) right: (decimal_integer_literal))))))))