public static int beautifulDays(int i, int j, int k)
    {
        int reverse = 0,day = 0;
        for(int num=i ; num <= j ; num++){
            int temp = num;
            while(temp > 0){
                reverse = reverse * 10 + temp % 10;
                temp /= 10;
            }
            int diff = Math.Abs(num - reverse);
            if(diff%k == 0){
                day++;
            }
            reverse = 0;
        }
        return day;
    }