public static String solve ( int n ) {
  if ( n == 1 ) {
    return "-1" ;
  }
  String str = "2" ;
  char [ ] chars = new char [ n - 1 ] ;
  Arrays . fill ( chars , '3' ) ;
  str = str + new String ( chars ) ;
  return str ;
}

public static String solve ( int n ) { if ( n == 1 ) { return " - 1" ; } String str = "2" ; char [ ] chars = new char [ n - 1 ] ; Arrays . fill ( chars , '3' ) ; str = str + new String ( chars ) ; return str ; }
(method_declaration (modifiers) type: (type_identifier) name: (identifier) parameters: (formal_parameters (formal_parameter type: (integral_type) name: (identifier))) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) consequence: (block (return_statement (string_literal)))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_literal))) (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 (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (character_literal)))) (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (object_creation_expression type: (type_identifier) arguments: (argument_list (identifier)))))) (return_statement (identifier))))