def dist(p,q):
    res = 0.0
    for i in range(h):
        for j in range(w):
            if b[i][j]=="1":
                res += ((i-p)**2+(j-q)**2)**0.5
    return res

h,w = map(int,input().split())
b = [input() for _ in range(h)]
ans = 1e9
for i in range(h):
    ans = min(ans,dist(i,-1))
    ans = min(ans,dist(i,w))
for i in range(w):
    ans = min(ans,dist(-1,i))
    ans = min(ans,dist(h,i))
print(ans)