def prod(ma, mb, mod = 10**9+7):
    n = len(ma)
    ret = [[0]*n for _ in range(n)]
    for i in range(n):
        for j in range(n):
            for k in range(n):
                ret[i][j] += ma[i][k]*mb[k][j]
                ret[i][j] %= mod
    return ret

def powmat(ma, k, mod = 10**9+7):
    n = len(ma)
    ret = [[0]*n for _ in range(n)]
    for i in range(n):
        ret[i][i] = 1
    for _ in range(k):
        if k & 1:
            ret = prod(ret, ma, mod)
        ma = prod(ma, ma, mod)
        k >>= 1
        if k == 0: break
    return ret

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

A = [[1, 1, 1], [1, 0, 0], [0, 1, 0]]
Ak = powmat(A, k-3, 10)[0]

ret = 0
ret += Ak[0] * r
ret += Ak[1] * q
ret += Ak[2] * p
ret %= 10

print(ret)