uses crt;
var i,a,b:longint;
function nt(a:longint):boolean;
var i:longint;
begin
   i:=2;
   while(a>1)and(a mod i<>0)do inc(i);
   nt:=i=a;
end;
begin
clrscr;
   write('Nhap a,b: ');readln(a,b);
   write('Cac so nguyen to: ');
   for i:=a to b do if nt(i) then write(i,' ');
readln
end.   

program pht;
uses crt;
  var a, b, i, j, s: integer;
begin
      clrscr;
      write('Nhap a = '); readln(a);
      write('Nhap b = '); readln(b);
      writeln('Cac so ngto tu a den b la: ');
      for i:=a to b do
      begin
                s:=0;
                for j:=1 to i do if i mod j = 0 then s:=s+1;
                if s=2 then write(i:3);
      end;
      readln
end.