def mat_mul(A, B):
    size = len(A)
    res = [[0] * size for _ in range(size)]
    for i in range(size):
        for k in range(size):
            for j in range(size):
                res[i][j] += A[i][k] * B[k][j]
                res[i][j] %= mod
    return res


def mat_pow(A, n):
    size = len(A)
    res = [[0] * size for _ in range(size)]
    for i in range(size):
        res[i][i] = 1
    while n:
        if n & 1:
            res = mat_mul(res, A)
        A = mat_mul(A, A)
        n >>= 1
    return res


mod = 10 ** 9 + 7
a, b, n = map(int, input().split())

A = [[a, b], [1, 0]]
A = mat_pow(A, n-1)
print(A[0][0] % mod)