import sys
import math
from collections import deque,Counter
#sys.setrecursionlimit(10**7)
int1=lambda x: int(x)-1

inp=lambda :int(input())
mi=lambda :map(int,input().split())
li=lambda :list(mi())
mi1=lambda :map(int1,input().split())
li1=lambda :list(mi1())
mis=lambda :map(str,input().split())
lis=lambda :list(mis())

from collections import defaultdict
"""
d=defaultdict(int) #初期値 0
d=defaultdict(lambda:1) #初期値 1
"""

mod=10**9+7
Mod=998244353
INF=10**18
ans=0

def matmul(A,B,mod): # A,B: 行列
    res = [[0]*len(B[0]) for _ in [None]*len(A)]
    for i, resi in enumerate(res):
        for k, aik in enumerate(A[i]):
            for j,bkj in enumerate(B[k]):
                resi[j] += aik*bkj
                resi[j] %= mod
    return res
 
def matpow(A,p,mod): #A^p mod M
    if p%2:
        return matmul(A, matpow(A,p-1,mod),mod)
    elif p > 0:
        b = matpow(A,p//2,mod)
        return matmul(b,b,mod)
    else:
        return [[int(i==j) for j in range(len(A))] for i in range(len(A))]

a,b=mi()
n=inp()
x=[[2*a,b-a**2],[1,0]]
y=matpow(x,n-1,mod)
z=matmul(y,[[2*a],[2]],mod)
print(z[0][0])