import numpy as np

MOD = 10 ** 9 + 7
def pow(A, n):
    if n == 0:
        return np.eye(len(A))
    if n == 1:
        return A % MOD
    elif n % 2 == 0:
        return pow(np.dot(A, A) % MOD, n // 2)
    else:
        return np.dot(A, pow(A, n - 1)) % MOD

def calc(a, b, n):
    """
    x_n を計算する
    """
    A = np.array([
        [a, b],
        [1, 0]
    ], dtype="uint64")
    s = np.array([
        [1],
        [0]
    ], dtype="uint64")
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        sq = pow(A, n - 1)
        return np.dot(sq, s)[0][0]

if __name__ == "__main__":
    input_line = input().split(" ")
    print(calc(int(input_line[0]), int(input_line[1]), int(input_line[2])))