program baigiai;
uses crt;
var a,b,i,d,j,k:integer;
function ktnt(m:integer):boolean;
var l:integer;
begin
ktnt:=false;
if m<2 then exit;
for l:=2 to trunc(sqrt(m)) do
if m mod l=0 then exit;
ktnt:=true;
end;
begin
clrscr;
write('Nhap a: '); readln(a);
write('Nhap b: '); readln(b);
writeln('Cac so nguyen to la: ');
k:=0;
for i:=a to b do
begin
if ktnt(i) then
begin
write(i,' ');
k:=k+1;
end;
end;
if k=0 then write('Khong co nha.');
writeln;
while a<>b do
if a>b then a:=a-b else b:=b-a;
write('uocchunglonnhat la: ',a);
readln;
end.