#include <iostream>
#include <sstream>
#include <math.h>
#include <stack>
#include <set>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <cstdio>
#include <vector>
#include <iomanip>
using namespace std;

#define INF (1 << 30)
#define INFLL (1LL << 60)

#define PI 3.14159265359

int main() {
	int w,h;
	char c;
	cin >> w >> h >> c;
	for(int i = 0;i < h;i++){
		for(int j = 0;j < w;j++){
			if(c == 'B'){
				if(i % 2 == 0){
					if(j % 2 == 0) cout << "B";
					else cout << "W";
				}else{
					if(j % 2 == 0) cout << "W";
					else cout << "B";
				}
			}else{
				if(i % 2 == 0){
					if(j % 2 == 0) cout << "W";
					else cout << "B";
				}else{
					if(j % 2 == 0) cout << "B";
					else cout << "W";
				}
			}
		}
		cout << endl;
	}
	return 0;
}