#yuki707
import math

h,w=map(int,raw_input().split())
p=[]
q=[]
for i in xrange(h):
 p.append(raw_input())
for i in xrange(h):
 for j in xrange(w):
  if p[i][j]=='1':
   q.append((i+1,j+1))

res=float('inf')
for i in xrange(h+2):
 cols=range(1,w+1) if i==0 or i==h+1 else [0,w+1]
 for j in cols:
  temp=0
  for x,y in q:
   temp+=math.sqrt((i-x)**2+(j-y)**2)
  res=min(res,temp)
print "%.9f" % res