data nopit sinpit twopit allpit;
        infile 'c:/temp/quad.txt';
        drop dis;
        input a= b= c=;

        if a=0 then                     /*linear equation*/
        do;
                if b=0 and c ~=0 then output nopit;
                else if b=0 and c=0 then output allpit;
                else output sinpit;
        end;
        else                            /*quadratic equation*/
        do;
                dis= b**2 - 4 * a * c;          /*discriminant*/
                if dis < 0 then   output nopit;  /*no solution*/
                else if dis > 0 then output twopit;
                else output sinpit;
        end;

proc print data=nopit;
        title 'no solutions';

proc print data=allpit;
        title 'all solutions';

proc print data=sinpit;
        title 'single solution';

proc print data=twopit;
        title 'two solutions';

run;