$$c i , \cos t = 400$$
$t=2\pi n_{1}-i\ln(400-\sqrt{159999})\text{, }n_{1}\in \mathrm{Z}\text{, }u=ic$
$t=2\pi n_{2}-i\ln(\sqrt{159999}+400)\text{, }n_{2}\in \mathrm{Z}\text{, }u=ic$
