dxy=zip([1,0,-1,0],[0,1,0,-1])
def rec(x,y,cnt):
    C[y][x]=str(cnt)
    for dx,dy in dxy:
        nx,ny=x+dx,y+dy
        if 0<=nx<W and 0<=ny<H and C[ny][nx]=='.':
            rec(nx,ny,cnt)
W,H=map(int,raw_input().split())
C=[list(raw_input()) for i in xrange(H)]
cnt=0
for y in xrange(H):
    for x in xrange(W):
        if C[y][x]=='.':
            rec(x,y,cnt)
            cnt+=1
ans=100000
for y1 in xrange(H):
    for x1 in xrange(W):
        for y2 in xrange(H):
            for x2 in xrange(W):
                if C[y1][x1]=='0' and C[y2][x2]=='1':
                    ans=min(ans,abs(x1-x2)+abs(y1-y2))
print ans-1