from math import isqrt


mod = 1000000007

def mat_mul(a, b) :
    I, J, K = len(a), len(b[0]), len(b)
    c = [[0] * J for _ in range(I)]
    for i in range(I) :
        for j in range(J) :
            for k in range(K) :
                c[i][j] += a[i][k] * b[k][j]
            c[i][j] %= mod
    return c


def mat_pow(x, n):
    y = [[0] * len(x) for _ in range(len(x))]

    for i in range(len(x)):
        y[i][i] = 1

    while n > 0:
        if n & 1:
            y = mat_mul(x, y)
        x = mat_mul(x, x)
        n >>= 1

    return y

a, b = map(int, input().split())
n = int(input())
if isqrt(b) ** 2 == b:
	print((pow(a + isqrt(b), n, mod) + pow(a - isqrt(b), n, mod)) % mod)
else:
	A = [[a, b], [1, a]]
	M = mat_pow(A, n)
	print(M[0][0] * 2 % mod)