#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 100000000000000000


int main(){
	
	int w,h;
	cin>>w>>h;
	
	char c;
	cin>>c;
	
	char cc;
	if(c=='B')cc = 'W';
	else cc = 'B';
	
	vector<string> s(h,string(w,'.'));
	rep(i,h){
		rep(j,w){
			if((i+j)%2==0)s[i][j] = c;
			else s[i][j] = cc;
		}
	}
	
	rep(i,h){
		cout<<s[i]<<endl;
	}
	
	return 0;
}