public static void main ( String [ ] args ) {
  String s = sc . next ( ) ;
  int n = sc . nextInt ( ) ;
  String [ ] ss = new String [ 5 ] ;
  for ( int i = 0 ;
  i < s . length ( ) ;
  i ++ ) {
    ss [ i ] = s . charAt ( i ) + "" ;
  }
  List < String > list = new ArrayList < > ( ) ;
  for ( int i = 0 ;
  i < ss . length ;
  i ++ ) {
    for ( int j = 0 ;
    j < ss . length ;
    j ++ ) {
      list . add ( ss [ i ] + ss [ j ] ) ;
    }
  }
  System . out . println ( list . get ( n - 1 ) ) ;
}

public static void main ( String [ ] args ) { String s = sc . next ( ) ; int n = sc . nextInt ( ) ; String [ ] ss = new String [ 5 ] ; for ( int i = 0 ; i < s . length ( ) ; i ++ ) { ss [ i ] = s . charAt ( i ) + " " ; } List < String > list = new ArrayList < > ( ) ; for ( int i = 0 ; i < ss . length ; i ++ ) { for ( int j = 0 ; j < ss . length ; j ++ ) { list . add ( ss [ i ] + ss [ j ] ) ; } } System . out . println ( list . get ( n - 1 ) ) ; }
(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: (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: (array_type element: (type_identifier) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (type_identifier) dimensions: (dimensions_expr (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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (string_literal)))))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (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: (field_access object: (identifier) field: (identifier))) update: (update_expression (identifier)) body: (block (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (field_access object: (identifier) field: (identifier))) update: (update_expression (identifier)) body: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (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: (identifier) right: (decimal_integer_literal)))))))))