var a,b,i: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
   repeat
      write('a,b=');readln(a,b);   writeln;
   until a<b;
   write('Cac so nguyen to tu ',a,' den ',b,': ');
   for i:=a to b do if nt(i) then write(i,' ');
readln
end.

var a,b: integer;
i: integer;
Function nt(n:integer):boolean;
var i:integer;
begin
nt:=false;
for i:=2 to trunc(sqrt(n)) do
if n mod i=0 then exit;
if n<2 then exit;
nt:=true;
end;
begin
repeat
write('Nhap a truoc, b sau: '); read(a,b);
until a<b;
writeln('Cac so nguyen to tim duoc: ');
for i:=a to b do if nt(i) then write(i,' ');
end.