4 days? ok, no problem.
Day 1 : Back and light biceps
Day 2: Chest and light tris
On both these days you do the main bodypart first and finish off with the bis and tris
Day 3: Legs and shoulders
Day 4: Arms
Haha, typical rookie routine, all very well if you want the usual massive chest/ narrow shoulders, combined with no legs look.
I'd say, chest and back on the same day, old school arnie style, then arms/legs/shoulders all on their own day. Otherwise your legs get seriously short-changed. All depends on the individual I suppose but most would say legs need their own day.