p, q, r, k = map(int, input().split())
t = [[0] * 1000 for _ in range(64)]
for j in range(1000):
    t[0][j] = (j % 10 + j // 10 % 10 + j // 100) % 10 + j * 10 % 1000
for i in range(63):
    for j in range(1000):
        t[i + 1][j] = t[i][t[i][j]]
k -= 3
p %= 10
q %= 10
r %= 10
x = p * 100 + q * 10 + r
for i in range(64):
    if (k >> i) & 1:
        x = t[i][x]
print(x % 10)