How would I prove the validity of this argument using a written out truth tree?

$($step by step$)$

$($x$)($y$)($z$)($B$($x$)$B$($y$)$B$($z$)(($x$=$y$)($x$=$z$)($y$=$z$)))$

$($x$)($y$)($z$)($w$)($B$($x$)$B$($y$)$B$($z$)$B$($w$)(($x$=$y$)($x$=$z$)($x$=$w$)($y$=$z$)($y$=$w$)($z$=$w$)))$