This is the solution for c#, i used a c++ to c# converter to convert the code from the one provided for c++ 11 and get the original code(with the mistakes) of the problem because there was no code provided to debug

using System; using System.Linq;

class Program { static int[] month = new int[15];

static void UpdateLeapYear(int year)
{
    if (year % 400 == 0) 
    {
        month[2] = 29; //three
    }
    else if (year % 100 == 0) 
    {
        month[2] = 28; //two
    }
    else if (year % 4 == 0 && year % 100 != 0) //four
    {
        month[2] = 29;
    }
    else
    {
        month[2] = 28;
    }
}

static void StoreMonth()
{
    month[1] = 31;
    month[2] = 28;
    month[3] = 31;
    month[4] = 30;
    month[5] = 31;
    month[6] = 30;
    month[7] = 31;
    month[8] = 31;
    month[9] = 30;
    month[10] = 31;
    month[11] = 30;
    month[12] = 31;
}

static int FindLuckyDates(int d1, int m1, int y1, int d2, int m2, int y2)
{
    StoreMonth();

    int result = 0;

    while (true)
    {
        int x = d1;
        x = x * 100 + m1;
        x = x * 10000 + y1; //five
        if (x % 4 == 0 || x % 7 == 0) //one
        {
            result++;
        }
        if (d1 == d2 && m1 == m2 && y1 == y2)
        {
            break;
        }
        UpdateLeapYear(y1);
        d1++;
        if (d1 > month[m1])
        {
            m1++;
            d1 = 1;
            if (m1 > 12)
            {
                y1++;
                m1 = 1;
            }
        }
    }
    return result;
}

static void Main()
{
    string str = Console.ReadLine();
    int d1, m1, y1, d2, m2, y2;
    str = str.Replace('-', ' ');
    var parts = str.Split(' ').Select(int.Parse).ToArray();
    d1 = parts[0];
    m1 = parts[1];
    y1 = parts[2];
    d2 = parts[3];
    m2 = parts[4];
    y2 = parts[5];

    int result = FindLuckyDates(d1, m1, y1, d2, m2, y2);
    Console.WriteLine(result);
}

}