почему не работает код java? [закрыт]

public class happy {
    public static void main(String[] args) {
        Scanner num = new Scanner (System.in);
        int first, second, result;
        System.out.print("Enter first num: ");
        first = num.nextInt();
        System.out.print("Enter second num: ");
        second = num.nextInt();
        result = first + second;
        System.out.println("It is" + result + "!!!");
    }
}

happy.java:3: error: cannot find symbol
                Scanner num = new Scanner (System.in);
                ^
  symbol:   class Scanner
  location: class happy
happy.java:3: error: cannot find symbol
                Scanner num = new Scanner (System.in);
                                  ^
  symbol:   class Scanner
  location: class happy
2 errors