import sys

def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
md = 10**9+7

def dot(aa, bb):
    h = len(aa)
    w = len(bb[0])
    res = [[0]*w for _ in range(h)]
    for i, row in enumerate(aa):
        for j, col in enumerate(zip(*bb)):
            v = 0
            # for a, b in zip(row, col): v += a*b
            # res[i][j] = v%md
            for a, b in zip(row, col): v += a*b%md
            res[i][j] = v%md
    return res

def matpow(mat, e):
    n = len(mat)
    res = [[1 if i == j else 0 for j in range(n)] for i in range(n)]
    while e:
        if e & 1: res = dot(res, mat)
        mat = dot(mat, mat)
        e >>= 1
    return res

a, b = LI()
s = (-a**2+b)%md
n = II()

mat = [[2*a%md, 1],
       [s, 0]]

cc = matpow(mat, n-1)
ans = dot([[2*a, 2]], cc)
print(ans[0][0])