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 % 1000000007;
			q %= Math.pow(10 , 9) + 7;			
			if(q < 0) q += 1000000007;
			long r = 1;
			long s = 0;
			n--;
			while(n != 0){
				if((n & 1) == 1){
					long x_tmp, y_tmp, z_tmp, w_tmp;
					x_tmp = x * p % 1000000007 + y * r % 1000000007;
					x_tmp %= Math.pow(10 , 9) + 7;
					y_tmp = x * q % 1000000007 + y * s % 1000000007;
					y_tmp %= Math.pow(10 , 9) + 7;
					z_tmp = z * p % 1000000007 + w * r % 1000000007;
					z_tmp %= Math.pow(10 , 9) + 7;
					w_tmp = z * q % 1000000007 + w * s % 1000000007;
					w_tmp %= Math.pow(10 , 9) + 7;
					x = x_tmp;
					y = y_tmp;
					z = z_tmp;
					w = w_tmp;
				}
				long p_tmp, q_tmp, r_tmp, s_tmp;
				p_tmp = p * p % 1000000007 + q * r % 1000000007;
				p_tmp %= Math.pow(10 , 9) + 7;
				q_tmp = p * q % 1000000007 + q * s % 1000000007;
				q_tmp %= Math.pow(10 , 9) + 7;
				r_tmp = p * r % 1000000007 + r * s % 1000000007;
				r_tmp %= Math.pow(10 , 9) + 7;
				s_tmp = r * q % 1000000007 + s * s % 1000000007;
				s_tmp %= Math.pow(10 , 9) + 7;
				p = p_tmp;
				q = q_tmp;
				r = r_tmp;
				s = s_tmp;
				n >>= 1;
			}
			x = 2 * a * x % 1000000007 + 2 * y % 1000000007;
			x %= Math.pow(10 , 9) + 7;
			while(x < 0) x += Math.pow(10 , 9) + 7;
			ou.println(x);
		}
		ou.flush();
		sc.close();
	}
}