def Matprod(A, B, mod):
    N = len(A)
    temp = [[0] * N for i in range(N)]
    for i in range(N):
        for j in range(N):
            for k in range(N):
                temp[i][j] += A[i][k] * B[k][j]
                temp[i][j] %= mod
    return temp

def Matpow(A, M, mod):
    N = len(A)
    Mat = [[0] * N for i in range(N)]
    for i in range(N):
        Mat[i][i] = 1
         
    for i in range(64):
        if (M >> i) & 1:
            Mat = Matprod(Mat, A, mod)
        A = Matprod(A, A, mod)
    return Mat     


a, b, n = map(int, input().split())
mod = 10**9 + 7
if n <= 1:
    print(n)
    exit()
    
Mat = [[a, b], [1, 0]]
Mat = Matpow(Mat, n - 1, mod)
print( Mat[0][0] % mod )