#include <iostream>
#include <iomanip>

#include <algorithm>
#include <string>
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////
int L[100000];

int main(void){
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout << fixed;//
	//cout << setprecision(7);//
	
	int W,H;
	string C;
	cin>>W>>H>>C;
	string gara[2];
	if(C[0] == 'B'){
		gara[0] = 'B';
		gara[1] = 'W';
	}else{
		gara[0] = 'W';
		gara[1] = 'B';
	}

	rep(i,W*H){
		if( ( (i/W)%2 + i%W)%2 == 0){
			cout << gara[0];
		}else{
			cout << gara[1];
		}
		if(i%W == W-1){
			cout << '\n';
		}
	}

	return 0;
}