  The initial boundary value problem on a half-line for the KdV equation with
the boundary conditions $u|_{x=0}=a\leq0$, $u_{xx}|_{x=0}=3a^2$ is integrated
by means of the inverse scattering method. In order to find the time evolution
of the scattering matrix it turned out to be sufficient to solve the Riemann
problem on a hyperelliptic curve of genus two, where the conjugation matrices
are effectively defined by initial data.
