mod = 10


def mat_mul(A, B):
    res = [[0] * len(B[0]) for _ in range(len(A))]
    for i in range(len(A)):
        for k in range(len(A[0])):
            for j in range(len(B[0])):
                res[i][j] += A[i][k] * B[k][j]
                res[i][j] %= mod
    return res


def mat_pow(A, n):
    size = len(A)
    res = [[0] * size for _ in range(size)]
    for i in range(size):
        res[i][i] = 1
    while n:
        if n & 1:
            res = mat_mul(res, A)
        A = mat_mul(A, A)
        n >>= 1
    return res


p, q, r, k = map(int, input().split())
p %= mod
q %= mod
r %= mod

a, b, c = p, q, r
k -= 1
if k < 3:
    print([p, q, r][k])
    exit()

A = [[1, 1, 1], [1, 0, 0], [0, 1, 0]]
A = mat_pow(A, k - 2)
ans = A[0][0] * r + A[0][1] * q + A[0][2] * p
ans %= mod
print(ans % mod)