def mat_mul(A, B):
    C = [[0 for _ in range(len(B[0]))] for _ in range(len(A))]
    
    for i in range(len(A)):
        for j in range(len(B[0])):
            for k in range(len(B)):
                C[i][j] = (C[i][j] + A[i][k] * B[k][j]) % MOD
    
    return C
 
def mat_pow(A, n):
    res = [[0 for _ in range(len(A))] for _ in range(len(A))]
    
    for i in range(len(A)):
        res[i][i] = 1
    
    while n > 0:
        if n & 1:
            res = mat_mul(res, A)
        A = mat_mul(A, A)
        n >>= 1
    
    return res

a, b, n = map(int, input().split())
MOD = 10**9 + 7
A = [[a, b], [1, 0]]
A = mat_pow(A, n)
print(A[1][0])