mod=10**9+7

def prod(a,b):
    ret=[[0,0],[0,0]]
    for i in range(2):
        for j in range(2):
            for k in range(2):
                ret[i][j]+=a[i][k]*b[k][j]
            ret[i][j]%=mod
    return ret

a,b=map(int,input().split())
n=int(input())
a1=2*a
a2=2*(a**2+b)
if n==0:
    print(2)
elif n==1:
    print(a1)
elif n==2:
    print(a2)
else:
    n-=2
    mat=[[1,0],[0,1]]
    coef=[[2*a,-(a**2-b)],[1,0]]
    for i in range(60):
        if n&(2**i):
            mat=prod(mat,coef)
        coef=prod(coef,coef)
    print((mat[0][0]*a2+mat[0][1]*a1)%mod)