N=int(input())
A=list(map(int,input().split()))
L=[]
for i in range(N):
  L.append((A[i],i))
L.sort(reverse=True)
result=['B']*N
x=L[0][0]
y=0
for i in range(1,N):
  z=L[i][0]
  if x&z:
    x|=z
  else:
    pos=L[i][1]
    result[pos]='W'
    y|=z
print(x*y)
print(*result,sep='')