Array expand with one formula

Question

input:

A 4
B 3
C 2

output:

A
A
A
A
B
B
B
C
C

Using only one formula. no code please.

Answer 1

=ArrayFormula(IFERROR(TRANSPOSE(SPLIT(CONCATENATE(REPT(A:A&CHAR(9);B:B));CHAR(9)))))