$ time perl min_supply.pl 1 4 3
Required supply: 3
6 steps:
   S->X
   X->Z
   S->X
   X->Z
   S->X
   X->Z

real    0m0.011s
user    0m0.016s
sys     0m0.000s

$ time perl min_steps.pl 1 4 3
3 steps:
   S->Y
   Y->Z
   Z->X

real    0m0.011s
user    0m0.008s
sys     0m0.004s

$ time perl -e1

real    0m0.002s
user    0m0.000s
sys     0m0.000s