# Read input
W, H, C = input().split()
W = int(W)
H = int(H)

# Determine the other color
other = 'B' if C == 'W' else 'W'

# Generate each row
for i in range(H):
    row = []
    for j in range(W):
        if (i + j) % 2 == 0:
            row.append(C)
        else:
            row.append(other)
    print(''.join(row))