X=[]
loop{
  x=[]
  x[0],x[1]=gets.split(" ").map{|v|v=v.to_i}
  X.push(x) if x!=[0,0]
  break if x==[0,0]
}
W1=[]
W2=[]
0.upto(150){|n|
  W1.push("#",".")
  W2.push(".","#")
}
0.upto(X.length-1){|m|
  t = X[m]
  h = t[0]
  w = t[1]
  1.upto(h){|o|
    puts W1[0..w-1].join if o%2!=0
    puts W2[0..w-1].join if o%2==0
  }
  puts ""
}