import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        int b = scan.nextInt();
        long t = scan.nextLong();
        long size = 1;
        for(long i =0; i < t; ++i){
            size = (a*size/2) + (b*size/2) % 1000000007L;
        }

        System.out.println(size);
    }


}