public static void main ( String [ ] args ) {
  try ( Scanner scanner = new Scanner ( System . in ) ) {
    int n = scanner . nextInt ( ) ;
    scanner . nextInt ( ) ;
    scanner . nextLine ( ) ;
    Set < Integer > commonSet = new HashSet < > ( ) ;
    IntStream . range ( 0 , n ) . forEach ( i -> {
      int number = scanner . nextInt ( ) ;
      Set < Integer > set = new HashSet < > ( ) ;
      IntStream . range ( 0 , number ) . forEach ( j -> set . add ( scanner . nextInt ( ) ) ) ;
      scanner . nextLine ( ) ;
      if ( 0 == i ) {
        commonSet . addAll ( set ) ;
      }
      else {
        Set < Integer > removeSet = new HashSet < > ( ) ;
        for ( Integer integer : commonSet ) {
          if ( ! set . contains ( integer ) ) {
            removeSet . add ( integer ) ;
          }
        }
        commonSet . removeAll ( removeSet ) ;
      }
    }
    ) ;
    System . out . println ( commonSet . size ( ) ) ;
  }
}

public static void main ( String [ ] args ) { try ( Scanner scanner = new Scanner ( System . in ) ) { int n = scanner . nextInt ( ) ; scanner . nextInt ( ) ; scanner . nextLine ( ) ; Set < Integer > commonSet = new HashSet < > ( ) ; IntStream . range ( 0 , n ) . forEach ( i -> { int number = scanner . nextInt ( ) ; Set < Integer > set = new HashSet < > ( ) ; IntStream . range ( 0 , number ) . forEach ( j -> set . add ( scanner . nextInt ( ) ) ) ; scanner . nextLine ( ) ; if ( 0 == i ) { commonSet . addAll ( set ) ; } else { Set < Integer > removeSet = new HashSet < > ( ) ; for ( Integer integer : commonSet ) { if ( ! set . contains ( integer ) ) { removeSet . add ( integer ) ; } } commonSet . removeAll ( removeSet ) ; } } ) ; System . out . println ( commonSet . size ( ) ) ; } }
(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 (try_with_resources_statement resources: (resource_specification (resource type: (type_identifier) name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) (expression_statement (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)))) (expression_statement (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (decimal_integer_literal) (identifier))) name: (identifier) arguments: (argument_list (lambda_expression parameters: (identifier) body: (block (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: (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)))) (expression_statement (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (decimal_integer_literal) (identifier))) name: (identifier) arguments: (argument_list (lambda_expression parameters: (identifier) body: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) (if_statement condition: (parenthesized_expression (binary_expression left: (decimal_integer_literal) right: (identifier))) consequence: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) alternative: (block (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)))) (enhanced_for_statement type: (type_identifier) name: (identifier) value: (identifier) body: (block (if_statement condition: (parenthesized_expression (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) consequence: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))))))))) (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)))))))))