import math
a=[]
i=0
while 1:
    l=input().split()

    h=int(l[0])
    w=int(l[1])

    if h==0 and w==0:
        break
    else:
        a.append(h)
        a.append(w)
        i=i+2

m=0
while m<i:
    while a[m]>0:
        if a[m]%2==0:
            if a[m+1]%2==0:
                b=a[m+1]/2
                print(int(b)*".#")
            else:
                b=math.floor(a[m+1]/2)
                print(int(b)*".#"+".")
        else:
            if a[m+1]%2==0:
                b=a[m+1]/2
                print(int(b)*"#.")
            else:
                b=math.floor(a[m+1]/2)
                print(int(b)*"#."+"#")
        a[m]=a[m]-1
    print("")
    m=m+2

