Calculation for a map with a bigger number gives invalid solution

[g1eng]

Problem

Input with a bigger number may give invalid solution for the map (and its length).

Example

echo 35182823158192831295815581123193910002 | cola2 
35182823158192831295815581123193910002 767 # <-- invalid

echo 35182823158192831295815581123193910002 | cola2 -d 
35182823158192831295815581123193910002 -> 17591411579096415647907790561596955001 -> 52774234737289246943723371684790865004 -> 26387117368644623471861685842395432502 -> 13193558684322311735930842921197716251 -> 39580676052966935207792528763593148754 -> 19790338026483467603896264381796574377 -> 59371014079450402811688793145389723132 -> 29685507039725201405844396572694861566 -> 14842753519862600702922198286347430783 -> 44528260559587802108766594859042292350 -> 22264130279793901054383297429521146175 -> 66792390839381703163149892288563438526 -> 33396195419690851581574946144281719263 -> 100188586259072554744724838432845157790 -> 50094293129536277372362419216422578895 -> 150282879388608832117087257649267736686 -> 75141439694304416058543628824633868343 -> 225424319082913248175630886473901605030 -> 112712159541456624087815443236950802515 -> 338136478624369872263446329710852407546 -> 169068239312184936131723164855426203773 -> ### **_166922351015616344931794887134510399864_** -> ...
...
 20 -> 10 -> 5 -> 16 -> 8 -> 4 -> 2 -> 1 [len=767]   ##<- invalid  (real: 1084)

Request

• This seems to overflow at hop 23 calculation of the map, and results invalid path for the conversion.
• Detect overflow and do not allow to show overflowed result.

[g1eng]

Another approach is under preparation to avoid this type of overflow at around 2^128. (451f2ee).
This commit includes bigint for the uint stack and it can successfully calculate map over 2^128 (but so slow at now).

u128 maybe should be a main type of the default solver but bigint can be optional way to calculate upper domain of maps.