from collections import deque

H, W = map(int, input().split())
A, B = map(lambda x: int(x)-1, input().split())
R1, C1, R2, C2 = map(lambda x: int(x)-1, input().split())
P, Q = map(lambda x: int(x)-1, input().split())

vector = [(1, 0), (0, 1), (-1, 0), (0, -1)]

dist1 = [[10**4]*W for _ in range(H)]
dist1[A][B] = 0
queue = deque()
queue.append((A, B))

while queue:
  i, j  = queue.popleft()
  for vi, vj in vector:
    if 0 <= i+vi < H and 0 <= j + vj < W and dist1[i+vi][j+vj] == 10**4:
      dist1[i+vi][j+vj] = dist1[i][j] + 1
      queue.append((i+vi, j+vj))

dist2 = [[10**4]*W for _ in range(H)]
dist2[P][Q] = 0
queue = deque()
queue.append((P, Q))

while queue:
  i, j  = queue.popleft()
  for vi, vj in vector:
    if 0 <= i+vi < H and 0 <= j + vj < W and dist2[i+vi][j+vj] == 10**4:
      dist2[i+vi][j+vj] = dist2[i][j] + 1
      queue.append((i+vi, j+vj))

ans = 10**18

for i in range(R1, R2+1):
  for j in range(C1, C2+1):
    ans = min(ans, dist1[i][j] + dist2[i][j] + dist2[A][B])

print(ans)