先入 さきい先出 さきだしリストであれば
sakiiresakidashirisutodeareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of 先入れ先出しリスト

1. If it were a first-in, first-out list.; If it is a first-in, first-out list.

Ba Conditional
Computing