Take any RNA that has greater than 65% GC bonds. Select GC bonds that are not on the end of a string (in this case, a series of stacks, made individual by separation from other string by loops of any kind) and mutate the G’s to A’s and the C’s to U’s. The dot plot should remain nearly identical, the energy will be lowered, and the structure will, in most cases, remain stable.
Excluding the ends of the string and GC’s necessary to retain the structure of the RNA, for every UA that exists inside of a short string (s long) instead of a GC, give half of a point to the RNA.