Underflow in Fortran
 

I try to run such Fortran program:

a= 1.0e-25

b= 1.0e-15

c= a * b

print *,a,b,c

end

but Fortran compiler Salford FTN77, ver. 4.03 for Win-95 give run-time error "float underflow". Can anybody say how to remedy this and to get simply c=0.0 ? Thanks.