from collections import deque
W,H=map(int,input().split())
C=["*"*(W+2) for _ in range(H+2)]
P=[]
J=[(-1,0),(1,0),(0,-1),(0,1)]

for x in range(1,H+1):
    C[x]="*"+input()+"*"
    for y in range(1,W+1):
        if C[x][y]==".":
            P.append((x,y))

inf=float("inf")
X,Y=P[0]
Dist=[[inf]*(W+2) for _ in range(H+2)]
Dist[X][Y]=0
Q=deque([(X,Y)])

while Q:
    X,Y=Q.popleft()
    for (u,v) in J:
        try:
            assert 0<=X+u<=H+1 and 0<=Y+v<=W+1
            c=1*(C[X+u][Y+v]!=".")
            if Dist[X][Y]+c<Dist[X+u][Y+v]:
                Dist[X+u][Y+v]=Dist[X][Y]+c
                if c==0:
                    Q.appendleft((X+u,Y+v))
                else:
                    Q.append((X+u,Y+v))
        except:
            pass

R=[Dist[X][Y] for (X,Y) in P if Dist[X][Y]>0]
print(min(R))