from collections import Counter

infile=open("ash.txt")
elfs={(x,y)
       for y, line in enumerate(infile)
       for x,ch in enumerate(line) if ch == '#'}

considerations=[((0,-1),(1,-1),(-1,-1)),
                ((0,1),(1,1),(-1,1)),
                ((-1,0),(-1,1),(-1,-1)),
                ((1,0),(1,1),(1,-1))]

def vis():
    xmin=min(elf[0] for elf in elfs)
    ymin=min(elf[1] for elf in elfs)
    xmax=max(elf[0] for elf in elfs)
    ymax=max(elf[1] for elf in elfs)
    empties=0
    for y in range(ymin, ymax+1):
        for x in range(xmin, xmax+1):
            if (x,y) in elfs:
                print("#", end="")
            else:
                print(".", end="")
                empties += 1
        print()
    print(empties)

for rnd in range(10000):
    props={}
    colls=Counter()
    for elf in elfs:
        if any((elf[0]+dx, elf[1]+dy) in elfs
               for dx in (-1,0,1)
               for dy in (-1,0,1) if dx != 0 or dy!=0):
            for cns in (considerations[(rnd+i)%4] for i in range(4)):
                if all((elf[0]+dx, elf[1]+dy) not in elfs for dx,dy in cns):
                    props[elf]=(elf[0]+cns[0][0],elf[1]+cns[0][1])
                    colls[props[elf]]+=1
                    break
            else:
                props[elf]=elf
        else:
            props[elf]=elf
    elfs.clear()
    moves=0
    for elf, prop in props.items():
        if colls[prop] <= 1:
            if elf != prop:
                moves += 1
            elfs.add(prop)
        else:
            elfs.add(elf)
    if moves == 0:
        break
#vis()
print (rnd+1)