Счастливое число

// HomeWork-Week-11.cpp :
//

#include <iostream>
using namespace std;
void luckyNumber()
{
    int sum1 = 0;
    int sum2 = 0;
    int d;
    int i = 1;
    int num;
again:

    while (true)
    {
        cin >> num;
        if (num < 0)
        {
            goto again;
        }
        while (num > 0)
        {
            d = num % 10;
            if (i % 2 == 0)
                sum2 += d;
            else
                sum1 += d;
            num = num / 10;
            i++;
        }
        if (sum1 == sum2)
        {
            cout << "Lucky number" << endl;
        }
        else
        {
            cout << "Unlucky number" << endl;
        }
    }
}

int main()
{
    //lucky number
    luckyNumber();
}