program SNT;

uses crt;

var n,i: integer;

Begin

         clrscr;

         write('Nhap n: '); readln(n);

         if n<=1 then write('n khong la so nguyen to')

         else

         begin

                  i:=2;

                  while n mod i<>0 do i:=i+1;

                  if i=n then write(n,' la so nguyen to')

                  else write(n,' khong la so nguyen to');

         end;

         readln

End.

program chuongtrinh;
var n,i:integer;
begin
writeln('nhap so n');readln(n);
if n < 2 then write('khong phai so nguyen to');
for i:=2 to round(sqrt(n)) do
if n mod i = 0 then write('n khong la so nguyen to');
if n mod i <> 0 then  write('n la so nguyen to');
readln;
end.