mod = 10 ** 9 + 7
def matrix_multiplication(a, b):
    n = len(a)
    res = [[0] * n for i in range(n)]
    for i in range(n):
        for k in range(n):
            for j in range(n):
                res[i][j] += a[i][k] * b[k][j]
                res[i][j] %= mod
    return res
def matrix_pow(a, k):
    n = len(a)
    res = [[0] * n for i in range(n)]
    for i in range(n):
        res[i][i] = 1
    while k:
        if k & 1:
            res = matrix_multiplication(res, a)
        a = matrix_multiplication(a, a)
        k >>= 1
    return res

a, b, n = map(int, input().split())
M = [[a, b], [1, 0]]
print(matrix_pow(M, n - 1)[0][0])