from copy import *
n,m = map(int, input().split())
grid = [list(map(int, input().split()))for i in range(n)]
mx = -1
ll = 1000000000
for i in range(n):
for j in range(m):
mx = max(mx, grid[i][j])
ll = min(ll, grid[i][j])
minmaxl = [[(float("inf"), -1)for i in range(m)]for i in range(n)]
minmaxr = [[(float("inf"), -1)for i in range(m)]for i in range(n)]
def setup():
for i in range(n-1,-1,-1):
minmaxl[i][0] = [grid[i][0], grid[i][0]]
for j in range(1,m):
minmaxl[i][j] = (min(minmaxl[i][j-1][0], grid[i][j]),max(minmaxl[i][j-1][1], grid[i][j]))
if i != n-1:
for j in range(m):
minmaxl[i][j] = (min(minmaxl[i][j][0], minmaxl[i+1][j][0]),max(minmaxl[i][j][1], minmaxl[i+1][j][1]))
for i in range(n-1,-1,-1):
minmaxr[i][m-1] = (grid[i][m-1], grid[i][m-1])
for j in range(m-2,-1,-1):
minmaxr[i][j] = (min(minmaxr[i][j+1][0], grid[i][j]),max(minmaxr[i][j+1][1], grid[i][j]))
if i != n-1:
for j in range(m-1,-1,-1):
minmaxr[i][j] = (min(minmaxr[i][j][0], minmaxr[i+1][j][0]),max(minmaxr[i][j][1], minmaxr[i+1][j][1]))
def check(a):
mini = float("inf")
maxi = -1
for i in range(n):
for j in range(m):
if mx - minmaxl[i][j][0] > a:
mini = min(mini, grid[i][j])
maxi = max(maxi, grid[i][j])
if maxi - mini <= a:
return True
mini = float("inf")
maxi = -1
for i in range(n):
for j in range(m):
if minmaxl[i][j][1]-ll > a:
mini = min(mini, grid[i][j])
maxi = max(maxi, grid[i][j])
if maxi - mini <= a:
return True
mini = float("inf")
maxi = -1
for i in range(n):
for j in range(m):
if mx - minmaxr[i][j][0] > a:
mini = min(mini, grid[i][j])
maxi = max(maxi, grid[i][j])
if maxi - mini <= a:
return True
mini = float("inf")
maxi = -1
for i in range(n):
for j in range(m):
if minmaxr[i][j][1]-ll > a:
mini = min(mini, grid[i][j])
maxi = max(maxi, grid[i][j])
if maxi - mini <= a:
return True
return False
setup()
lo = 0
hi = 10000000000
while (lo<hi):
mid = (lo+hi)//2
if check(mid):
hi = mid
else:
lo = mid+1
ans = lo
print(ans)
