public static void main ( String [ ] args ) throws IOException {
  input . init ( System . in ) ;
  PrintWriter out = new PrintWriter ( System . out ) ;
  int n = input . nextInt ( ) ;
  int [ ] as = new int [ n ] , bs = new int [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) as [ i ] = input . nextInt ( ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) bs [ i ] = input . nextInt ( ) ;
  long res = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    if ( as [ i ] + as [ i ] < bs [ i ] || bs [ i ] == 1 ) res -- ;
    else {
      int a = bs [ i ] / 2 , b = bs [ i ] - a ;
      if ( b > as [ i ] ) {
        b = as [ i ] ;
        a = bs [ i ] - as [ i ] ;
      }
      res += ( long ) a * b ;
    }
  }
  out . println ( res ) ;
  out . close ( ) ;
}

public static void main ( String [ ] args ) throws IOException { input . init ( System . in ) ; PrintWriter out = new PrintWriter ( System . out ) ; int n = input . nextInt ( ) ; int [ ] as = new int [ n ] , bs = new int [ n ] ; for ( int i = 0 ; i < n ; i ++ ) as [ i ] = input . nextInt ( ) ; for ( int i = 0 ; i < n ; i ++ ) bs [ i ] = input . nextInt ( ) ; long res = 0 ; for ( int i = 0 ; i < n ; i ++ ) { if ( as [ i ] + as [ i ] < bs [ i ] || bs [ i ] == 1 ) res -- ; else { int a = bs [ i ] / 2 , b = bs [ i ] - a ; if ( b > as [ i ] ) { b = as [ i ] ; a = bs [ i ] - as [ i ] ; } res += ( long ) a * b ; } } out . println ( res ) ; out . close ( ) ; }
(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 (expression_statement (method_invocation object: (identifier) name: (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: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier)))) 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))))) (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))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (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: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (identifier))) right: (array_access array: (identifier) index: (identifier))) right: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (decimal_integer_literal)))) consequence: (expression_statement (update_expression (identifier))) alternative: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (decimal_integer_literal))) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (identifier)))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (array_access array: (identifier) index: (identifier)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (array_access array: (identifier) index: (identifier)))) (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (identifier))))))) (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (cast_expression type: (integral_type) value: (identifier)) right: (identifier)))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))