2 10 50
  Ncall2 and Itmx2 are the number of integrand
calls for one iteration and number of iterations
for the second (main) step of integration.  The
grid constructed on the first step is used but
the integral estimate obtained on the first step
is not used for event generation.
  While using the stratified sampling method it is 
desirable to increase Ncall2, taking into account 
that the time of calculation is proportional to 
Ncall2*Itmx2.