import numpy as np

A, B, N = map(int, input().split())
MOD = 10 ** 9 + 7


def pow_matrix_mod(x, n, mod=MOD):
    if not n:
        return np.eye(len(x), dtype=np.object)
    if n % 2 == 0:
        return pow_matrix_mod(x @ x % mod, n // 2) % mod
    else:
        return x @ pow_matrix_mod(x @ x % mod, (n - 1) // 2) % mod


if A == 0 and B == 0:
    ans = 1 if N == 1 else 0
elif A == 0:
    ans = pow(B, N // 2, MOD) if N % 2 else 0
elif B == 0:
    ans = pow(A, N - 1, MOD) if N else 0
else:
    X = np.array([[0, 1], [B, A]])
    ans = pow_matrix_mod(X, N)[0, 1]
print(ans)