  Let f(x,y)=0 be an equation of plane analytic curve defined in the
neighborhood of the origin and let $\pi:M\to(\Cn^2,0)$ be a local toric
modification. We give a formula which connects a number of double points
\delta_0(f)$ with a sum $\sum_p \delta_p(\tilde f)$ which runs over all
intersection points of the proper preimage of f=0 with the exceptional divisor.
