  Most of the common used models of epidemic spreading allow contaminating many
neighbors of a particular node in the network. They are usually analyzed by
differential equations on probability vectors. We propose a model of epidemic
spreading, which restricts to at most one contamination per time step and
analyze it by discrete approach, working on vectors of possible states of the
system. Theoretical predictions of epidemic treshold, stationary state and time
needed to reach it are given and appear to be perfectly consistent with
computer simulations. We also point ou that the model appears to be well suited
to mimic epidemic spreading within student communes.
