Программирование Pascal abc

 var 
  D,a,b,c : real; 
begin 
  writeln('ax^2+bx+c=0'); 
  write('a=');  
  readln(a); 
  write('b=');  
  readln(b); 
  write('c=');  
  readln(c); 
  D:= b**2 - (4*a*c); 
  writeln('D=',D); 
  if D < 0 then 
    write('Нет корней') 
  else 
    if D = 0 then 
      write('x=',-b/(2*a)) 
    else 
      begin 
        writeln('x1=',(-b-sqrt(D))/(2*a)); 
        writeln('x2=',(-b+sqrt(D))/(2*a)); 
      end; 
end.