class Problem0082:
	def swap(this, c):
		if c == "B":
			return "W"
		else:
			return "B"
	
	def solve(this):
		w,h,c = input().split()
		for i in range(int(h)):
			res = ""
			
			t = c
			for j in range(int(w)):
				res += t
				t = this.swap(t)
			print(res)
			c = this.swap(c)
			
if __name__ == "__main__":
	problem = Problem0082()
	problem.solve()