#include <iostream>
using namespace std;

int w,h;
char c[] = {'W','B'};

int main(){
    char tmp;
    cin >> w >> h >> tmp;
    int i = (tmp == 'W') ? 0 : 1;
    for(int j = 0;j < h;j++){
        for(int k = 0;k < w;k++){
            cout << c[i];
            i = (i + 1)%2;
        }
        cout << endl;
        if (tmp == c[i])
            i = (i+1)%2;
            tmp = c[i];
    }
}