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]=(b=l[i]<?.)?0:t[i]+1
y=y.map{|j|j<d ?j:d}<<d
k=-1
x=b ?[0]*(i+1):(x<<0).map{|j|o=y[k+=1]*v=j+1;m<o&&m=o;v}}}
p m
end