e=enumerate;H,F='HF'
def f(m):
 h=len(m)-1;w=len(q:=m[0])-1;o=0;n=lambda m,c,d:[[c if(k,l)in(g:=lambda c:{(k,l)for i,r in e(m)for j,v in e(r)for k in[i-1,i,i+1]for l in[j-1,j,j+1]if v==c and h>=k>-1<l<=w})(c)-g(d)else m[k][l]for(l,v)in e(r)]for(k,r)in e(m)];l=lambda:all(~-(H in r)for r in a)
 while a:=m:
  while~-(H in[q]+[a[h]]+[r[0]for r in a]+[r[w]for r in a]or l()):a=n(n(a,H,F),F,1)
  if l():return o
  else:
   o+=1;d=1
   for i in(0,h):
    for j,v in e(a[i]):
     if(v==H)*d:m[i][j+h//2]=F;d=0
   for j in(0,w):
    for i,v in e(r[j]for r in a):
     if(v==H)*d:m[i+w//2][j]=F;d=0
 
import pprint
 
examples=[
"""FFFFF
F...F
F.H.F
F...F
FFFFF""",
"""FFFFF
F....
F....
F....
F.H..
F....
F....
F....
FFFFF""",
""".....
.....
..H..
.....
....."""]
 
for s in examples:
    m0 = [[v for(l,v)in e(r)]for(k,r)in e(s.split("\n"))] # splits string into a matrix
    pprint.pprint(m0)
    print(f(m0))

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