from collections import defaultdict
h, w = map(int, input().split())
p = [input() for i in range(h)]
black = []
for i in range(h):
    for g in range(w):
        if p[i][g] == "1":
            black.append((i+1, g+1))

red = defaultdict(float)
for i in range(1, h+1):
    for x, y in black:
        red[(i, 0)] += ((x-i)**2 + (y)**2)**0.5
        red[(i, w+1)] += ((x-i)**2 + (y-w-1)**2)**0.5


for i in range(1, w+1):
    for x, y in black:
        red[(0, i)] += ((x)**2 + (y-i)**2)**0.5
        red[(h+1, i)] += ((x-h-1)**2 + (y-i)**2)**0.5

if red == {}:
    print(0)
else:
    print(min(red.values()))