public static void main ( String [ ] args ) {
  Scanner in = new Scanner ( System . in ) ;
  int n = in . nextInt ( ) , i , l = 0 , r = n - 1 , c [ ] = new int [ n ] ;
  for ( i = 0 ;
  i < n ;
  i ++ ) c [ i ] = in . nextInt ( ) ;
  in . close ( ) ;
  while ( c [ l ] == c [ n - 1 ] ) l ++ ;
  while ( c [ r ] == c [ 0 ] ) r -- ;
  System . out . println ( Math . max ( n - l - 1 , r ) ) ;
}

public static void main ( String [ ] args ) { Scanner in = new Scanner ( System . in ) ; int n = in . nextInt ( ) , i , l = 0 , r = n - 1 , c [ ] = new int [ n ] ; for ( i = 0 ; i < n ; i ++ ) c [ i ] = in . nextInt ( ) ; in . close ( ) ; while ( c [ l ] == c [ n - 1 ] ) l ++ ; while ( c [ r ] == c [ 0 ] ) r -- ; System . out . println ( Math . max ( n - l - 1 , r ) ) ; }
(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))) declarator: (variable_declarator name: (identifier)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (decimal_integer_literal))) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier))))) (for_statement init: (assignment_expression left: (identifier) right: (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))) (while_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))))) body: (expression_statement (update_expression (identifier)))) (while_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (decimal_integer_literal)))) body: (expression_statement (update_expression (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 (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal)) (identifier))))))))