program oken;
uses crt;
var n,i,dem:longint;
begin
clrscr;
write('nhap n: '); readln(n);
for i:=2 to n-1 do
if n mod i =0 then dem :=dem+1;
if dem=0 then writeln(n,' la so nguyen to');
if (n=0) or (n=1) or (dem>0) then writeln(n,' khong phai la so nguyen to');
readln;
end.