p,q,r,k = map(int,input().split())
mod = 10
def calc(a,b):
    ans = [[0]*3 for i in range(3)]
    for i in range(3):
        for j in range(3):
            for m in range(3):
                ans[i][j] += a[i][m]*b[m][j]
                ans[i][j] %= mod
    return ans

A = [[1,1,1],[1,0,0],[0,1,0]]

B = [[0]*3 for i in range(3)]
for i in range(3):
    B[i][i] = 1
k -= 3
while k:
    if k%2:
        B = calc(B,A)
    A = calc(A,A)
    k //= 2
ans = B[0][0]*r+B[0][1]*q+B[0][2]*p
print(ans%mod)