from copy import deepcopy
MOD = 10 ** 9 + 7

def matpow(A, B, w):
    l = len(A)
    while w:
        if w & 1:
            C = [0] * l
            for i in range(l):
                for j in range(l):
                    C[i] += A[i][j] * B[j]
                    C[i] %= MOD
            B = C.copy()
        C = [[0] * l for _ in range(l)]
        for i in range(l):
            for j in range(l):
                for k in range(l):
                    C[i][j] += A[i][k] * A[k][j]
                    C[i][j] %= MOD
        A = deepcopy(C)
        w >>= 1
    return B
    
a, b, n = map(int, input().split())
A = [[a, b], [1, 0]]
B = [1, 0]
B = matpow(A, B, n - 1)
print(B[0])