For distinct complex numbers [tex] \rm z_1,z_2, \cdots, z_{673},[/tex] the polynomial
[tex] \rm(x - z_1 {)}^3(x - z_2 {)}^3 \dots(x - z_{673} {)}^3[/tex]
can be expressed as
[tex] \rm {x}^{2019} + 20 {x}^{2018} + {19}x^{2017} + g(x),[/tex]
where g(x) is a polynomial with complex coefficients and with degree at most 2016.
[tex] \rm The \: value \: of \left | \sum \limits_{1 \leq j < k \leq673 }z_{j} z_k\right| [/tex]
can be expressed in the form m/n, where m and n are relatively prime positive integers. Find m+n.​