  We study the symbol of the two-loop n-gluon MHV amplitude for all Mandelstam
regions in multi-Regge kinematics in N=4 super Yang-Mills theory. While the
number of distinct Mandelstam regions grows exponentially with n, the increase
of independent symbols turns out to be merely quadratic. We uncover how to
construct the symbols for any number of external gluons from just two building
blocks which are naturally associated with the six- and seven-gluon amplitude,
respectively. The second building block is entirely new, and in addition to its
symbol, we also construct a prototype function that correctly reproduces all
terms of maximal functional transcendentality.
