P,Q,R,K=map(int,input().split())
P%=10
Q%=10
R%=10
mod=10
def m(a,b):
  r=[[0]*len(b[0]) for i in range(len(a))]
  for i in range(len(a)):
    for k in range(len(b)):
      for j in range(len(b[0])):
        r[i][j]=(r[i][j]+a[i][k]*b[k][j])%mod
  return r

def p(a,n):
  r=[[0]*len(a) for i in range(len(a))]
  b=[]
  for i in range(len(a)):
    r[i][i]=1
    b.append(a[i][:])
  l=n
  while l>0:
    if l&1:
      r=m(b,r)
    b=m(b,b)
    l>>=1
  return r

if K==1:
  print(P)
if K==2:
  print(Q)
if K==3:
  print(R)
if K<=3:
  exit()
X=[[0,0,0],[0,0,0],[0,0,0]]
X[0][0]=1
X[0][1]=1
X[0][2]=1
X[1][0]=1
X[2][1]=1
Y=[[0]*3 for i in range(3)]
Y[0][2]=R
Y[1][2]=Q
Y[2][2]=P
print(m(p(X,K-3),Y)[0][2])