import java.io.*;
import java.util.*;
import java.math.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();
        BigInteger t = in.nextBigInteger();
        //int t = in.nextInt();
        BigInteger modulo = new BigInteger("1000000007");
        Integer nu = (int)(0.5*(a+b));
        BigInteger plus = new BigInteger("1");
        BigInteger num = new BigInteger(nu.toString()); 
        //System.out.println("num: " + num.toString() + " t: " + t.toString());
        while (!t.equals(new BigInteger("1"))) {
            if (!t.mod(new BigInteger("2")).equals(new BigInteger("0"))) {
                plus = plus.multiply(num);
            }
            num = num.multiply(num);
            num = num.mod(modulo);
            t = t.divide(new BigInteger("2"));
            //System.out.println("num: " + num.toString() + " t: " + t.toString());
        }
        num = num.multiply(plus);
        num = num.mod(modulo);
        //System.out.println(plus);
        System.out.println(num);
    }
}