program kaito;
uses crt;
var n, i: integer;
begin
clrscr;
write('Nhap so N: '); readln(n);
if n<2 then writeln('Day khong phai so nguyen to') else
while n mod i <> 0 do inc(i);
begin
if i=n then writeln('Day la so nguyen to')
else writeln('Day khong phai so nguyen to');
end;
readln
end.
CHÚC BẠN HỌC TỐT!!!