public static void main ( String [ ] args ) {
  java . util . Scanner sc = new java . util . Scanner ( System . in ) ;
  int n = sc . nextInt ( ) , m = 0 , l = 2000001 , a [ ] = new int [ l ] , pre [ ] = new int [ l ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) a [ sc . nextInt ( ) ] ++ ;
  for ( int i = 1 ;
  i < l ;
  i ++ ) if ( a [ i - 1 ] > 0 ) pre [ i ] = i - 1 ;
  else pre [ i ] = pre [ i - 1 ] ;
  for ( int i = 1 ;
  i < l ;
  i ++ ) if ( a [ i ] > 0 ) for ( int j = i * 2 ;
  j < l ;
  j += i ) m = Math . max ( m , pre [ j ] % i ) ;
  System . out . println ( m ) ;
}

public static void main ( String [ ] args ) { java . util . Scanner sc = new java . util . Scanner ( System . in ) ; int n = sc . nextInt ( ) , m = 0 , l = 2000001 , a [ ] = new int [ l ] , pre [ ] = new int [ l ] ; for ( int i = 0 ; i < n ; i ++ ) a [ sc . nextInt ( ) ] ++ ; for ( int i = 1 ; i < l ; i ++ ) if ( a [ i - 1 ] > 0 ) pre [ i ] = i - 1 ; else pre [ i ] = pre [ i - 1 ] ; for ( int i = 1 ; i < l ; i ++ ) if ( a [ i ] > 0 ) for ( int j = i * 2 ; j < l ; j += i ) m = Math . max ( m , pre [ j ] % i ) ; System . out . println ( m ) ; }
(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: (scoped_type_identifier (scoped_type_identifier (type_identifier) (type_identifier)) (type_identifier)) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (scoped_type_identifier (scoped_type_identifier (type_identifier) (type_identifier)) (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))) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier)))) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) 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 (update_expression (array_access array: (identifier) index: (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: (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (decimal_integer_literal))) consequence: (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) alternative: (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (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: (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (decimal_integer_literal))) consequence: (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (decimal_integer_literal)))) condition: (binary_expression left: (identifier) right: (identifier)) update: (assignment_expression left: (identifier) right: (identifier)) body: (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (identifier))))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))