s=input()
ss=s.split()
w=int(ss[0])
h=int(ss[1])
c=ss[2]
for i in range(0,h):
    a=""
    for j in range(0,w):
        if c=='B':
            if i%2==0:
                if j%2==0:
                    a+='B'
                if j%2==1:
                    a+='W'
            elif i%2==1:
                if j%2==0:
                    a+='W'
                if j%2==1:
                    a+='B'
        elif c=='W':
            if i%2==0:
                if j%2==0:
                    a+='W'
                if j%2==1:
                    a+='B'
            elif i%2==1:
                if j%2==0:
                    a+='B'
                if j%2==1:
                    a+='W'
    print(a)