using System;
using System.Collections.Generic;
using System.IO;
class Solution {
    public static class Virus{
        private const float probA = 0.5f;
        private const float probB = 0.5f;
        private static List<int> _intGrowth = new List<int>();
        private static int _intTime;
        
        public static List<int> Growth{
            get { return _intGrowth; }
            set { _intGrowth = value; }
        }
        
        public static int Time{
            get { return _intTime; }
            set { _intTime = value; }
        }
        
        public static void ReadLine(string value){
            Growth.Add(Convert.ToInt32(value.Split(' ')[0]));
            Growth.Add(Convert.ToInt32(value.Split(' ')[1]));
            Time = Convert.ToInt32(value.Split(' ')[2]);
        }
        
        public static void Display(){
            int result = (int)(((probA * Growth[0] * Time) + (probB * Growth[1] * Time)) % (Math.Pow(10, 9) + 7));
            Console.WriteLine(result);
        }
    }
    static void Main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */
        Virus.ReadLine(Console.ReadLine().Trim());
        Virus.Display();
    }
}