using System;
using System.Globalization;
class Program
{
    public static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        DateTime firstDate = DateTime
            .ParseExact(Console.ReadLine(), "dd-MM-yyyy", CultureInfo.InvariantCulture)
            .AddDays(n / 2 + n % 2);
        DateTime secondDate = DateTime
            .ParseExact(Console.ReadLine(), "dd-MM-yyyy", CultureInfo.InvariantCulture)
            .AddDays(n / 2);
        Console.WriteLine(firstDate.Day + secondDate.Day);
    }
}