import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def FI(): return float(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MF(): return map(float, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
inf = 10**16
# md = 998244353
md = 10**9+7

h,w=MI()
pp=[]
for i in range(h):
    s=SI()
    for j,c in enumerate(s):
        if c=="1":pp.append((i,j))

ans=inf
for i in range(h):
    s=0
    for x,y in pp:
        s+=((i-x)**2+(-1-y)**2)**0.5
    ans=min(ans,s)
    s=0
    for x,y in pp:
        s+=((i-x)**2+(w-y)**2)**0.5
    ans=min(ans,s)
for j in range(w):
    s=0
    for x,y in pp:
        s+=((-1-x)**2+(j-y)**2)**0.5
    ans=min(ans,s)
    s=0
    for x,y in pp:
        s+=((h-x)**2+(j-y)**2)**0.5
    ans=min(ans,s)

print(ans)