public static void main ( String [ ] args ) throws IOException {
  Scanner input = new Scanner ( System . in ) ;
  String x = input . next ( ) ;
  Stack < Character > stk = new Stack < > ( ) ;
  for ( int i = x . length ( ) - 1 ;
  i >= 0 ;
  i -- ) {
    if ( ! stk . empty ( ) && stk . peek ( ) == x . charAt ( i ) ) {
      stk . pop ( ) ;
    }
    else stk . push ( x . charAt ( i ) ) ;
  }
  int size = stk . size ( ) ;
  StringBuffer ans = new StringBuffer ( "" ) ;
  for ( int i = 0 ;
  i < size ;
  i ++ ) ans . append ( stk . pop ( ) ) ;
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) throws IOException { Scanner input = new Scanner ( System . in ) ; String x = input . next ( ) ; Stack < Character > stk = new Stack < > ( ) ; for ( int i = x . length ( ) - 1 ; i >= 0 ; i -- ) { if ( ! stk . empty ( ) && stk . peek ( ) == x . charAt ( i ) ) { stk . pop ( ) ; } else stk . push ( x . charAt ( i ) ) ; } int size = stk . size ( ) ; StringBuffer ans = new StringBuffer ( " " ) ; for ( int i = 0 ; i < size ; i ++ ) ans . append ( stk . pop ( ) ) ; System . out . println ( ans ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) (throws (type_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: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) 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: (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: (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) right: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) consequence: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) alternative: (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (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: (object_creation_expression type: (type_identifier) arguments: (argument_list (string_literal))))) (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: (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))