import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def FI(): return float(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MF(): return map(float, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
inf = 10**16
# md = 998244353
md = 10**9+7

# af(n)+bf(n+1)+cf(n+2)+df(n+3)=f(n+4)みたいなとき
# coeff=[a,b,c,d]
# 初期値f0(f(0)からf(3))
class Fibonacci:
    def __init__(self, coeff, f0):
        self.f0 = f0
        n = len(coeff)
        ff = [[0]*n for _ in range(2*n-1)]
        for i in range(n): ff[i][i] = 1
        for i in range(n, 2*n-1):
            ffi = ff[i]
            for j, c in enumerate(coeff, i-n):
                ffj = ff[j]
                for k in range(n): ffi[k] += c*ffj[k]
        self.bn = 1 << (n-1).bit_length()
        self.base = ff[self.bn]
        self.ff = ff
        self.n = n

    def __mm(self, aa, bb):
        n = self.n
        res = [0]*(n*2-1)
        for i, a in enumerate(aa):
            for j, b in enumerate(bb):
                res[i+j] += a*b
                res[i+j] %= md
        for i in range(n, 2*n-1):
            c = res[i]
            ffi = self.ff[i]
            for j in range(n):
                res[j] += c*ffi[j]
                res[j] %= md
        return res[:n]

    def v(self, x):
        base = self.base
        aa = self.ff[x%self.bn]
        x //= self.bn
        while x:
            if x & 1: aa = self.__mm(aa, base)
            base = self.__mm(base, base)
            x >>= 1
        return sum(a*f%md for a, f in zip(aa, self.f0))%md

a, b, n = MI()
if a == b == 0:
    if n==1:print(1)
    else:print(0)
elif b == 0:
    print(pow(a, n-1, md))
else:
    fibo = Fibonacci([b, a], [0, 1])
    print(fibo.v(n))