import java.util.*;
import java.io.*;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		PrintWriter ou = new PrintWriter(System.out);
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
		long n = Long.parseLong(sc.next());
		if(n == 0) ou.println(2);
		else{
			long x = 1;
			long y = 0;
			long z = 0;
			long w = 1;
			long p = 2 * a;
			p %= (long)(Math.pow(10 , 9) + 7);
			long q = b - a * (long)a;
			q %= Math.pow(10 , 9) + 7;			
			long r = 1;
			long s = 0;
			n--;
			while(n != 0){
				if((n & 1) == 1){
					x = x * p + y * r;
					x %= Math.pow(10 , 9) + 7;
					y = x * q + y * s;
					y %= Math.pow(10 , 9) + 7;
					z = z * p + w * r;
					z %= Math.pow(10 , 9) + 7;
					w = z * q + w * s;
					w %= Math.pow(10 , 9) + 7;
				}
				p = p * p + q * r;
				p %= Math.pow(10 , 9) + 7;
				q = p * q + q * s;
				q %= Math.pow(10 , 9) + 7;
				r = p * r + r * s;
				r %= Math.pow(10 , 9) + 7;
				s = r * q + s * s;
				s %= Math.pow(10 , 9) + 7;
				n >>= 1;
			}
			x = 2 * a * x + 2 * y;
			x %= Math.pow(10 , 9) + 7;
			while(x < 0) x += Math.pow(10 , 9) + 7;
			ou.println(x);
		}
		ou.flush();
		sc.close();
	}
}