def mmult(A, B):
    global mod
    n, m, l = len(A), len(B), len(B[0])
    ret = [[0] * l for _ in range(n)]
    for i in range(n):
        for j in range(m):
            for k in range(l):
                ret[i][k] = (ret[i][k] + A[i][j] * B[j][k]) % mod
    return ret
def mpow(A, n):
    if n == 1: return A
    if n == 0: return [[1 if i == j else 0 for j in range(len(A))] for i in range(len(A))]
    return mmult(mpow(A, n - 1), A) if n % 2 else mpow(mmult(A, A), n // 2)

mod = 10
p, q, r, K = map(int, input().split())
X = [[0,0,1],[1,0,1],[0,1,1]]
print(mmult([[p, q, r]], mpow(X, K - 1))[0][0])