public static void main ( String [ ] args ) throws IOException {
  BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  String s = br . readLine ( ) ;
  String st [ ] = s . split ( "[+]" ) ;
  Arrays . sort ( st ) ;
  String res = "" ;
  for ( String i : st ) {
    res = res + i + "+" ;
  }
  System . out . println ( res . substring ( 0 , res . length ( ) - 1 ) ) ;
}

public static void main ( String [ ] args ) throws IOException { BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ; String s = br . readLine ( ) ; String st [ ] = s . split ( " [ + ] " ) ; Arrays . sort ( st ) ; String res = " " ; for ( String i : st ) { res = res + i + " + " ; } System . out . println ( res . substring ( 0 , res . length ( ) - 1 ) ) ; }
(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: (type_identifier) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_literal))) (enhanced_for_statement type: (type_identifier) name: (identifier) value: (identifier) body: (block (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (string_literal)))))) (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 (decimal_integer_literal) (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (decimal_integer_literal)))))))))