construct/rlve polynomial integer roots

construct/rlve polynomial integer roots: a task in MathConstructOptimize-Envs-harbor (Harbor dataset). The degree-3 polynomial P(x) = (-18) x^0 + (21) x^1 + (-8) x^2 + (1) x^3 can be written as (x - a 1)(x - a 2)...(x - a 3) with integers a 1, ..., a 3 (not necessarily distinct). Find such integers.