using System;
using System.Collections.Generic;
using System.IO;
class Solution
{
    static void Main(String[] args)
    {
        string[] tokens_a0 = Console.ReadLine().Split(' ');
        int a = Convert.ToInt32(tokens_a0[0]);
        int b = Convert.ToInt32(tokens_a0[1]);
        long t = Convert.ToInt32(tokens_a0[2]);
        long virusCell = a / 2 * t + b / 2 * t;
        long virusCellShort = virusCell % (1000000000 + 7);
        Console.WriteLine(virusCellShort);
        //Console.ReadKey();
    }
}