public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  String s = sc . next ( ) ;
  HashMap < String , Long > h = new HashMap < > ( ) ;
  for ( int i = 0 ;
  i < 1 << n ;
  i ++ ) {
    String red = "" ;
    String blue = "" ;
    for ( int j = 0 ;
    j < n ;
    j ++ ) {
      if ( ( i & ( 1 << j ) ) > 0 ) {
        red += s . charAt ( j ) ;
      }
      else {
        blue += s . charAt ( j ) ;
      }
    }
    String key = red + ":" + blue ;
    long tmp = h . getOrDefault ( key , 0L ) ;
    h . put ( key , tmp + 1 ) ;
  }
  long ans = 0 ;
  for ( int i = 0 ;
  i < 1 << n ;
  i ++ ) {
    String red = "" ;
    String blue = "" ;
    for ( int j = 0 ;
    j < n ;
    j ++ ) {
      if ( ( i & ( 1 << j ) ) > 0 ) {
        red += s . charAt ( 2 * n - 1 - j ) ;
      }
      else {
        blue += s . charAt ( 2 * n - 1 - j ) ;
      }
    }
    String key = red + ":" + blue ;
    long tmp = h . getOrDefault ( key , 0L ) ;
    ans += tmp ;
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; String s = sc . next ( ) ; HashMap < String , Long > h = new HashMap < > ( ) ; for ( int i = 0 ; i < 1 << n ; i ++ ) { String red = " " ; String blue = " " ; for ( int j = 0 ; j < n ; j ++ ) { if ( ( i & ( 1 << j ) ) > 0 ) { red += s . charAt ( j ) ; } else { blue += s . charAt ( j ) ; } } String key = red + " : " + blue ; long tmp = h . getOrDefault ( key , 0L ) ; h . put ( key , tmp + 1 ) ; } long ans = 0 ; for ( int i = 0 ; i < 1 << n ; i ++ ) { String red = " " ; String blue = " " ; for ( int j = 0 ; j < n ; j ++ ) { if ( ( i & ( 1 << j ) ) > 0 ) { red += s . charAt ( 2 * n - 1 - j ) ; } else { blue += s . charAt ( 2 * n - 1 - j ) ; } } String key = red + " : " + blue ; long tmp = h . getOrDefault ( key , 0L ) ; ans += tmp ; } 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: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier) (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments)) 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: (binary_expression left: (decimal_integer_literal) right: (identifier))) update: (update_expression (identifier)) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_literal))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_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: (parenthesized_expression (binary_expression left: (identifier) right: (parenthesized_expression (binary_expression left: (decimal_integer_literal) right: (identifier))))) right: (decimal_integer_literal))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))))))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (binary_expression left: (identifier) right: (string_literal)) right: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (decimal_integer_literal))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (binary_expression left: (identifier) right: (decimal_integer_literal))))))) (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: (binary_expression left: (decimal_integer_literal) right: (identifier))) update: (update_expression (identifier)) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_literal))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_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: (parenthesized_expression (binary_expression left: (identifier) right: (parenthesized_expression (binary_expression left: (decimal_integer_literal) right: (identifier))))) right: (decimal_integer_literal))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (binary_expression left: (binary_expression left: (decimal_integer_literal) right: (identifier)) right: (decimal_integer_literal)) right: (identifier))))))) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (binary_expression left: (binary_expression left: (decimal_integer_literal) right: (identifier)) right: (decimal_integer_literal)) right: (identifier)))))))))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (binary_expression left: (identifier) right: (string_literal)) right: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (decimal_integer_literal))))) (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))))))