import sys


def convTile(str):
    if str == "W":
        return "B"
    elif str == "B":
        return "W"
    else:
        return "-1"

l = input().split()
col = int(l[0])
idx = int(l[1])
tl = l[2]
arr = [[0 for i in range(col)] for j in range(idx)]

if col % 2 == 0:
    flag = 0
else:
    flag = -1

if flag == 0:
    for j in range(idx):
        for i in range(col):
            sys.stdout.write(tl)
            tl = convTile(tl)
        tl = convTile(tl)
        print()
else:
    for j in range(idx):
        for i in range(col):
            sys.stdout.write(tl)
            tl = convTile(tl)
        print()