# -*- coding:utf-8 -*-
if __name__ == '__main__':
    s = input().split()
    w, h = map(int, s[:2])
    c = s[2]
    bw = "BW" * int(w / 2 + 1)
    index = c == 'W'
    for i in range(h):
        print(bw[index:w+index])
        index = not index