program NTO; uses crt;
var n, i: integer;
KT: Boolean;
begin
clrscr;
write('Nhap n bat ki: '); readln(n);
if n< 2 then Kt:=false
else Kt:=true;
for i:= 2 to trunc(sqrt(n)) do
if n mod i = 0 then
begin
Kt:=false;
break;
end;
if Kt=true then write('La so nguyen to')
else
write('Khong phai la so nguyen to');
readln;
end.
