while(h,w=gets.split.map &:to_i)[0]>0
t=[m=0]*w
h.times{l=gets
x=[[]]
y=[[]]
w.times{|i|d=t[i]=l[i]<?.?0:t[i]+1
y[i]=y[-1].map{|j|j<d ?j:d}<<d
k=-1
x[i]=(x[-1]+[0]).map{|j|o=y[i][k+=1]*v=l[i]<?.?0:j+1;m<o&&m=o;v}}}
p m
end