type Times10<B extends readonly unknown[]> = [
  ...B, ...B, ...B, ...B, ...B, ...B, ...B, ...B, ...B, ...B
]

type Build<S extends string, C extends readonly unknown[] = []> =
  S extends `${infer Head extends keyof A}${infer Rest}` ? Build<Rest, [...Times10<C>, ...A[Head]]> : C

type ConstructTuple<L extends number> = Build<`${L}`>

import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<MinusOne<1>, 0>>,
  Expect<Equal<MinusOne<55>, 54>>,
  Expect<Equal<MinusOne<3>, 2>>,
  Expect<Equal<MinusOne<100>, 99>>,
  Expect<Equal<MinusOne<1101>, 1100>>,
]