mod = 10
p, q, r, k = map(int, input().split())
def mul(A, B):
    n = len(A)
    C = [[0]*n for _ in range(n)]
    for i in range(n):
        for j in range(n):
            for k in range(n):
                C[i][j] += A[i][k] * B[k][j]
                C[i][j] %= mod
    return C
def mpow(A, n):
    if n == 1:
        return A
    if n%2:
        return mul(mpow(A, n-1), A)
    B = mpow(A, n//2)
    return mul(B, B)
A = [[0,1,0], [0,0,1], [1,1,1]]
B = mpow(A, k-3)
ans = B[-1][0]*p + B[-1][1]*q + B[-1][2]*r
ans %= mod
print(ans)