public static void main ( String [ ] args ) {
  Scanner scan = new Scanner ( System . in ) ;
  PrintWriter pr = new PrintWriter ( System . out ) ;
  int n = scan . nextInt ( ) ;
  int a = scan . nextInt ( ) ;
  int first , diff , numTerms ;
  if ( a % 2 == 1 ) {
    first = 1 ;
    diff = 2 ;
  }
  else {
    first = n ;
    diff = - 2 ;
  }
  long sum = ( ( a - first ) / diff + 1 ) ;
  System . out . print ( sum ) ;
}

public static void main ( String [ ] args ) { Scanner scan = new Scanner ( System . in ) ; PrintWriter pr = new PrintWriter ( System . out ) ; int n = scan . nextInt ( ) ; int a = scan . nextInt ( ) ; int first , diff , numTerms ; if ( a % 2 == 1 ) { first = 1 ; diff = 2 ; } else { first = n ; diff = - 2 ; } long sum = ( ( a - first ) / diff + 1 ) ; System . out . print ( sum ) ; }
(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: (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: (integral_type) declarator: (variable_declarator name: (identifier)) declarator: (variable_declarator name: (identifier)) declarator: (variable_declarator name: (identifier))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (decimal_integer_literal))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal))) (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal)))) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (identifier))) (expression_statement (assignment_expression left: (identifier) right: (unary_expression operand: (decimal_integer_literal)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (parenthesized_expression (binary_expression left: (binary_expression left: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) right: (identifier)) right: (decimal_integer_literal))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))