using System.Numerics;

public class Program
{
    public static void Main()
    {

        //int num = int.Parse(Console.ReadLine() ?? string.Empty);
        string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        //string str = Console.ReadLine() ?? string.Empty;


        int a = int.Parse(str[0]);
        int b = int.Parse(str[1]);

        double d = double.Parse(str[2]);
        int c=(a + b) + (int)((a + b) * d);
        Console.WriteLine(c);

    }

}