from copy import deepcopy

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

B = [r, q, p]
A = [[1, 1, 1], 
     [1, 0, 0],
     [0, 1, 0]]

K -= 3
while K:
    if K & 1:
        C = [0, 0, 0]
        for i in range(3):
            for j in range(3):
                C[i] += A[i][j] * B[j]
            C[i] %= 10
        B = C.copy()
    C = [[0] * 3 for _ in range(3)]
    for i in range(3):
        for j in range(3):
            for k in range(3):
                C[i][j] += A[i][k] * A[k][j]
            C[i][j] %= 10
    A = deepcopy(C)
    K >>= 1
print(B[0])