public static void main ( String [ ] args ) throws Exception {
  BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  String s = br . readLine ( ) ;
  Stack < Character > stk = new Stack < Character > ( ) ;
  for ( int i = 0 ;
  i < s . length ( ) ;
  i ++ ) {
    if ( stk . empty ( ) ) {
      stk . push ( s . charAt ( i ) ) ;
    }
    else {
      if ( stk . peek ( ) != s . charAt ( i ) ) stk . push ( s . charAt ( i ) ) ;
      else stk . pop ( ) ;
    }
  }
  StringBuilder sb = new StringBuilder ( ) ;
  while ( ! stk . empty ( ) ) sb . append ( stk . pop ( ) ) ;
  System . out . println ( sb . reverse ( ) . toString ( ) ) ;
}

public static void main ( String [ ] args ) throws Exception { BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ; String s = br . readLine ( ) ; Stack < Character > stk = new Stack < Character > ( ) ; for ( int i = 0 ; i < s . length ( ) ; i ++ ) { if ( stk . empty ( ) ) { stk . push ( s . charAt ( i ) ) ; } else { if ( stk . peek ( ) != s . charAt ( i ) ) stk . push ( s . charAt ( i ) ) ; else stk . pop ( ) ; } } StringBuilder sb = new StringBuilder ( ) ; while ( ! stk . empty ( ) ) sb . append ( stk . pop ( ) ) ; System . out . println ( sb . reverse ( ) . toString ( ) ) ; }
(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 (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 (type_identifier))) 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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) consequence: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))))) alternative: (block (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) consequence: (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) alternative: (expression_statement (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)))) (while_statement condition: (parenthesized_expression (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) 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 (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) name: (identifier) arguments: (argument_list)))))))