W,H,C=input().split()

W=int(W)
H=int(H)

if C=="B":
    A=[["B"]*W for i in range(H)]

    for i in range(H):
        for j in range(W):
            if (i+j)%2==1:
                A[i][j]="W"

else:
    A=[["W"]*W for i in range(H)]

    for i in range(H):
        for j in range(W):
            if (i+j)%2==1:
                A[i][j]="B"

for i in range(H):
    print("".join(A[i]))