# import platform
# ver = platform.python_version_tuple()
# if int(ver[1]) < 5:
#     from fractions import gcd
# else:
#     from math import gcd

# from itertools import accumulate, combinations, permutations, product
# from bisect import bisect, bisect_left
# from collections import Counter, defaultdict, deque
# from heapq import heappush, heappop

# from decimal import *
# getcontext().prec = 500

# from functools import lru_cache
# @lru_cache(maxsize=1024)

from sys import stdin, stdout
input = lambda: stdin.readline().rstrip()
write = stdout.write

def main():

    position = []
    for i in range(1, H + 1):
        position.append((0, i))
        position.append((W + 1, i))
    for i in range(1, W + 1):
        position.append((i, 0))
        position.append((i, H + 1))

    dist = float('inf')
    for x, y in position:
        dist = min(dist, calc(x, y))
    print(dist)

def calc(x1, y1):
    ret = 0
    for y2, s1 in enumerate(P, start=1):
        for x2, s2 in enumerate(s1, start=1):
            if s2 == '1':
                ret += ((x1 - x2) ** 2 + (y1 - y2) ** 2) ** 0.5
    return ret

H, W = map(int, input().split())
P = stdin.read().splitlines()
main()