N = int(input())
A = list(map(int, input().split()))

L = 12
b = [[] for _ in range(L)]
for i in range(N):
    for bit in range(L - 1, -1, -1):
        if (A[i] >> bit) & 1:
            b[bit].append(i)
            break

W, B = 0, 0
ans = ["W"] * N
for bit in range(L - 1, -1, -1):
    b[bit].sort(reverse=True)

    if W == 0:
        for i in b[bit]:
            W |= A[i]
            ans[i] = 'W'
    else:
        for i in b[bit]:
            if W & A[i] == 0:
                B |= A[i]
                ans[i] = 'B'
            else:
                W |= A[i]
                ans[i] = 'W'


print(W * B)
print("".join(ans))