import sys


def input(): return sys.stdin.readline().rstrip()


def main():
    W, H, C = input().split()
    for i in range(int(H)):
        for j in range(int(W)):
            if ((i+j) % 2 == 0) == (C == 'W'):
                print('W', end='')
            else:
                print('B', end='')
        print()


if __name__ == '__main__':
    main()