public static void main ( String args [ ] ) {
  FastScanner input = new FastScanner ( ) ;
  String s = input . next ( ) ;
  long ans = 0 ;
  long temp = 0 ;
  for ( int i = s . length ( ) - 1 ;
  i >= 0 ;
  i -- ) {
    if ( s . charAt ( i ) == 'b' ) {
      temp ++ ;
    }
    else {
      ans += temp ;
      temp *= 2 ;
      ans = ans % mod ;
      temp = temp % mod ;
    }
  }
  System . out . println ( ans ) ;
}

public static void main ( String args [ ] ) { FastScanner input = new FastScanner ( ) ; String s = input . next ( ) ; long ans = 0 ; long temp = 0 ; for ( int i = s . length ( ) - 1 ; i >= 0 ; i -- ) { if ( s . charAt ( i ) == ' b ' ) { temp ++ ; } else { ans += temp ; temp *= 2 ; ans = ans % mod ; temp = temp % mod ; } } System . out . println ( ans ) ; }
(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)))) (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))) (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)) right: (decimal_integer_literal)))) condition: (binary_expression left: (identifier) right: (decimal_integer_literal)) 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)))) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (identifier))) (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal))) (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (identifier)))) (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (identifier)))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))