h,w=map(int,input().split())
p=[[0]+[0]*w+[0]]
for i in range(h):
  p+=[[0]+list(map(int,input()))+[0]]
p+=[[0]+[0]*w+[0]]
a=10**10
for i in range(h+2):
  j=0
  na=0
  for ii in range(1,1+h):
    for jj in range(1,1+w):
      na+=(((ii-i)**2+(jj-j)**2)**0.5)*p[ii][jj]
  a=min(a,na)
  j=w+1
  na=0
  for ii in range(1,1+h):
    for jj in range(1,1+w):
      na+=(((ii-i)**2+(jj-j)**2)**0.5)*p[ii][jj]
  a=min(a,na)
for j in range(w+2):
  i=0
  na=0
  for ii in range(1,1+h):
    for jj in range(1,1+w):
      na+=(((ii-i)**2+(jj-j)**2)**0.5)*p[ii][jj]
  a=min(a,na)
  i=h+1
  na=0
  for ii in range(1,1+h):
    for jj in range(1,1+w):
      na+=(((ii-i)**2+(jj-j)**2)**0.5)*p[ii][jj]
  a=min(a,na)
print(a)