n,m=map(int,input().split())
a=list(map(int,input().split()))
b=list(map(int,input().split()))
e=[[] for i in range((m+1)*n)]
for i in range(m+1):
  for j in range(n):
    if j+1<n:
      e[i*n+j]+=[(i*n+j+1,1)]
    if j-1>=0:
      e[i*n+j]+=[(i*n+j-1,1)]
for i in range(m):
  for j in range(n):
    if a[j]==b[i]:
      e[i*n+j]+=[((i+1)*n+j,0)]
from collections import deque
q=deque()
X=10**10
v=[X]*(m+1)*n
v[0]=0
q.append((v[0],0))
while len(q)>0:
  sc,sp=q.popleft()
  for tp,tc in e[sp]:
    if v[tp]>sc+tc:
      v[tp]=sc+tc
      if tc:
        q.append((v[tp],tp))
      else:
        q.appendleft((v[tp],tp))
print(min(v[m*n:(m+1)*n]))