import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

a,b,n = map(int,read().split())

MOD = 10 ** 9 + 7

# x^n = p + qx mod x^2 - ax - b
def power(n):
    if n == 0:
        return 1,0
    p,q = power(n//2)
    p,q,r = p*p,2*p*q,q*q
    q += a * r; p += b * r
    p %= MOD
    q %= MOD
    if not n&1:
        return p,q
    p,q,r = 0,p,q
    q += a * r; p += b * r
    p %= MOD
    q %= MOD
    return p,q

p,q = power(n)
print(q)