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

public class Main {
    static final int MOD = 1000000007;
	public static void main (String[] args) throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] first = br.readLine().split(" ", 3);
		int a = Integer.parseInt(first[0]);
		int b = Integer.parseInt(first[1]);
		int n = Integer.parseInt(first[2]);
		long[][] xy = new long[31][4];
		xy[0] = new long[]{a, b, 1, 0};
		for (int i = 1; i < 31; i++) {
		    xy[i][0] = (xy[i - 1][0] * xy[i - 1][0] + xy[i - 1][1] * xy[i - 1][2]) % MOD;
		    xy[i][1] = (xy[i - 1][0] * xy[i - 1][1] + xy[i - 1][1] * xy[i - 1][3]) % MOD;
		    xy[i][2] = (xy[i - 1][2] * xy[i - 1][0] + xy[i - 1][3] * xy[i - 1][2]) % MOD;
		    xy[i][3] = (xy[i - 1][2] * xy[i - 1][1] + xy[i - 1][3] * xy[i - 1][3]) % MOD;
		}
		long x = 1;
		long y = 0;
		for (int i = 30; i >= 0 && n > 0; i--) {
		    if (n >= (1 << i)) {
		        n -= (1 << i);
		        long xx = (x * xy[i][0] + y * xy[i][1]) % MOD;
		        long yy = (x * xy[i][2] + y * xy[i][3]) % MOD;
		        x = xx;
		        y = yy;
		    }
		}
		System.out.println(y);
	}
}