public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int N = sc . nextInt ( ) ;
  int T = sc . nextInt ( ) ;
  int [ ] A = new int [ N ] ;
  for ( int i = 0 ;
  i < N ;
  ++ i ) A [ i ] = sc . nextInt ( ) ;
  sc . close ( ) ;
  int ans = 0 ;
  int currentTime = A [ 0 ] ;
  for ( int i = 1 ;
  i < N ;
  ++ i ) {
    if ( currentTime + T < A [ i ] ) {
      ans += T ;
    }
    else {
      ans += A [ i ] - A [ i - 1 ] ;
    }
    currentTime = A [ i ] ;
  }
  ans += T ;
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int N = sc . nextInt ( ) ; int T = sc . nextInt ( ) ; int [ ] A = new int [ N ] ; for ( int i = 0 ; i < N ; ++ i ) A [ i ] = sc . nextInt ( ) ; sc . close ( ) ; int ans = 0 ; int currentTime = A [ 0 ] ; for ( int i = 1 ; i < N ; ++ i ) { if ( currentTime + T < A [ i ] ) { ans += T ; } else { ans += A [ i ] - A [ i - 1 ] ; } currentTime = A [ i ] ; } ans += T ; 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))) 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: (integral_type) 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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier))))) (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 (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))))) (expression_statement (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: (array_access array: (identifier) index: (decimal_integer_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: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (array_access array: (identifier) index: (identifier)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (identifier)))) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal)))))))) (expression_statement (assignment_expression left: (identifier) right: (array_access array: (identifier) index: (identifier)))))) (expression_statement (assignment_expression left: (identifier) right: (identifier))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))