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

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner in = new Scanner(System.in);
        long a = in.nextLong();
        long b = in.nextLong();
        long t = in.nextLong();

        

        
        BigInteger result;
        BigInteger modValue = BigInteger.valueOf(7).add(BigInteger.valueOf((long)Math.pow(10, 9)));
        
        BigInteger aBig = BigInteger.valueOf(a);
        BigInteger bBig = BigInteger.valueOf(b);
        
        result = aBig.add(bBig).divide(BigInteger.valueOf(2)).modPow(BigInteger.valueOf(t), modValue);
        
        System.out.println(result);
    }
}