Sample SAS Code to Calculate the Number of Cells

/* Set the filename here, 
   excluding the extension,
   including the already-defined libname.
*/
%let dataset=libname.inputname;
%let personid=personid;
%let firmid=firmid;

proc sort data=&dataset.(keep=&personid. &firmid.);
   by &personid. &firmid.;
run;

data out;
   set dot.in;
      by &personid. &firmid.;

   if first.&firmid. then output;
run;

%let dsid = %sysfunc(open(out));
%let nobs=%sysfunc(attrn(&dsid,nobs));
%let rc = %sysfunc(close(&dsid));

%put =================================================;
%put   Your data &dataset. has &nobs. cells ;
%put =================================================;