  We consider N=2 SUSY QCD with gauge group SU(2) and N_f flavours of matter
with nonzero mass. Using the method of the instanton-induced effective vertex
we calculate higher derivative corrections to the Seiberg-Witten result in the
momentum expansion of the low energy effective Lagrangian in various regions of
the modular space. Then we focus on a certain higher derivative operator on the
Higgs branch. We show that the singular behavior of this operator comes from
values of mass of matter at which charge singularity on the Coulomb branch
collides with the monopole or dyon one. Given the behavior of this operator at
weak coupling coming from instantons as well as its behavior near points of
colliding singularities we find the exact solution for this operator.
