W, H, C = input().split()
W = int(W)
H = int(H)
ans = [['' for _ in range(W)] for _ in range(H)]
for i in range(H):
    for j in range(W):
        if (i+j)%2==0:
            ans[i][j] = C 
        else:
            if C=="B":
                ans[i][j] = "W"
            else:
                ans[i][j] = "B"
for a in ans:
    print("".join(a))