program ct;
uses crt;
var i,n:integer;
begin
clrscr;
write('nhap n:=');readln(n);
if n<=1 then writeln('N khong phai so nguyen to')
else
begin
i:=2;
while n mod i<>0 do i:=i+1;
if i=n then writeln(n,; la so nguyen to') else writeln(n,' khong la so nguyen to');
end;
readln
end.