public class Main{
	public static void main(String[] args){
		java.util.Scanner sc = new java.util.Scanner(System.in);
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next());
		long n = Long.parseLong(sc.next());
		if(n == 0){
			System.out.println(2);
			return;
		}
		Matrix x = new Matrix(1, 0, 0, 1);
		long tmp = (b - a * a % 1000000007) % 1000000007;
		if(tmp < 0) tmp += 1000000007;
		Matrix y = new Matrix(a * 2 % 1000000007, tmp, 1, 0);
		--n;
		while(n != 0){
			if((n & 1) == 1){
				x.mul(y);
			}
			y.mul(y);
			n >>= 1;
		}

		// System.out.println(x.x00 + " " + x.x01);
		// System.out.println(x.x10 + " " + x.x11);
		System.out.println((x.x00 * a * 2 % 1000000007 + x.x01 * 2 % 1000000007) % 1000000007);
	}
}

class Matrix{
	long x00, x01, x10, x11;
	public Matrix(long x00, long x01, long x10, long x11){
		this.x00 = x00;
		this.x01 = x01;
		this.x10 = x10;
		this.x11 = x11;
	}
	public void mul(Matrix a){
		long tmp00 = x00;
		long tmp01 = x01;
		long tmp10 = x10;
		long tmp11 = x11;
		long a00 = a.x00;
		long a01 = a.x01;
		long a10 = a.x10;
		long a11 = a.x11;
		this.x00 = (tmp00 * a00 % 1000000007 + tmp01 * a10 % 1000000007) % 1000000007;
		this.x01 = (tmp00 * a01 % 1000000007 + tmp01 * a11 % 1000000007) % 1000000007;
		this.x10 = (tmp10 * a00 % 1000000007 + tmp11 * a10 % 1000000007) % 1000000007;
		this.x11 = (tmp10 * a01 % 1000000007 + tmp11 * a11 % 1000000007) % 1000000007;
	}
}