Program Nguyen_to_1;
uses crt;
var n, i: integer;
ok: boolean;
begin
ok:=true;
write(‘Nhap n: ‘);readln(n);
for i:= 2 to n – 1 do if n mod i = 0 then
ok :=false;
if ok then write(n,’ la so nguyen to’)
else write(n, ‘ khong la so nguyen to’);
readln
end.