w,h,c=input().split()
w=int(w)
h=int(h)
for i in range(h):
    a=[]
    for j in range(w):
        if c=="B" and (i+j)%2==0 or c=="W" and (i+j)%2==1:
            a.append("B")
        else:
            a.append("W")
    print("".join(a))