#include <iostream>

using namespace std;
#define REP(i,n) for (int i=0;i<(n);i++)

int main()
{
	int W, H, bw;
	char C;
	cin >> W >> H >> C;
	bw = (C == 'B' ? 1 : 0);

	REP(i, H) {
		REP(j, W) {
			cout << ((i + j + bw) % 2 ? 'B' : 'W');
		}
		cout << endl;
	}
}