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

public class Main {
    static final int MOD = 1000000007;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int a = sc.nextInt();
        int b = sc.nextInt();
        int n = sc.nextInt();
        long[][][] matrix = new long[30][2][2];
        matrix[0] = new long[][]{{0, 1}, {b, a}};
        for (int i = 1; i < 30; i++) {
            for (int j = 0; j < 2; j++) {
                for (int k = 0; k < 2; k++) {
                    for (int l = 0; l < 2; l++) {
                        matrix[i][j][l] += matrix[i - 1][j][k] * matrix[i - 1][k][l] % MOD;
                        matrix[i][j][l] %= MOD;
                    }
                }
            }
        }
        long[] ans = new long[]{0, 1};
        for (int i = 29; i >= 0; i--) {
            if (n < (1 << i)) {
                continue;
            }
            n -= (1 << i);
            long[] next = new long[2];
            for (int j = 0; j < 2; j++) {
                for (int k = 0; k < 2; k++) {
                    next[j] += matrix[i][j][k] * ans[k] % MOD;
                    next[j] %= MOD;
                }
            }
            ans = next;
        }
        System.out.println(ans[0]);
    }
    
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}