The two subroutines in Figure 1 and Figure 2 are designed to count how many times a population $P$ can be halved before it falls to 1 or below.

Figure 1

SUBROUTINE countHalvings(P)
  count ← 0
  WHILE P > 1
    P ← P / 2
    count ← count + 1
  ENDWHILE
  OUTPUT count
ENDSUBROUTINE

Figure 2

SUBROUTINE countHalvings(P)
  count ← 0
  REPEAT
    P ← P / 2
    count ← count + 1
  UNTIL P ≤ 1
  OUTPUT count
ENDSUBROUTINE