N,Q=map(int, input().split())
A=list(map(int, input().split()))
B=list(map(int, input().split()))

D={}
for i in range(N):
  b=A[i]
  if b not in D:
    D[b]=[]
  D[b].append(i)

dp=[10**10]*N 
dp[0]=0
for b in B:
  nex=D[b]
  L=[10**10]*N;R=[10**10]*N;ndp=[10**10]*N 
  l=10**10;r=10**10
  for i in range(N):
    l=min(dp[i],l+1)
    if A[i]==b:
      ndp[i]=min(ndp[i],l)
    j=-1-i
    r=min(dp[j],r+1)
    if A[j]==b:
      ndp[j]=min(ndp[j],r) 
  dp=ndp

print(min(dp))