Integer firstIndex = 10; System.debug(firstIndex)
Standard input is empty
Object: Integer error: did not understand #firstIndex MessageNotUnderstood(Exception)>>signal (ExcHandling.st:254) Integer class(Object)>>doesNotUnderstand: #firstIndex (SysExcept.st:1448) UndefinedObject>>executeStatements (prog:1)
./prog:2: expected expression