import numpy as np

MOD = 10


def pow_matrix_mod(x, n, mod=MOD):
    x = x.astype(object)
    if not n:
        return np.eye(len(x), dtype=object)
    if n % 2 == 0:
        return pow_matrix_mod(x @ x % mod, n // 2) % mod
    else:
        return x @ pow_matrix_mod(x @ x % mod, (n - 1) // 2) % mod


*x, K = map(int, input().split())
M = np.array([[0, 0, 1],
              [1, 0, 1],
              [0, 1, 1]])
y = np.array(x) @ pow_matrix_mod(M, K - 3) % MOD
print(y[-1])