#include <bits/stdc++.h>
using namespace std;

int main() {
  int W, H;
  char C;
  cin >> W >> H >> C;

  char a[2] = {};
  if (C == 'B') {
    a[0] = 'B', a[1] = 'W';
  } else {
    a[0] = 'W', a[1] = 'B';
  }

  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      cout << a[(i + j) % 2];
    }
    cout << endl;
  }
}