#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream> 
#include<map>
#include <iomanip>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
using namespace std;
#define MAX_MOD 1000000007
#define REP(i,n) for(long long i = 0;i < n;++i)
#define LONG_INF 100000000000000
string wow[2] = { "B","W" };
int main() {
	int a, b;
	string c;
	cin >> a >> b >> c;
	for (int i = 0;i < b;++i) {
		for (int q = 0;q < a;++q) {
			if (c == "B") {
				cout << wow[(i + q) % 2];
			}
			else {
				cout << wow[(i + q + 1) % 2];
			}
		}
		cout << endl;
	}
	return 0;
}