#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
//constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;
const long double PI = acos((long double)(-1));

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;


int main()
{
    /*
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    */

    int W, H;
    char c; cin >> W >> H >> c;
    string t;
    t += c;
    if (c == 'B') t += 'W'; else t += 'B';
    vector<string> vs(H, string(W, ' '));
    for (int i = 0; i < H; i++) {
        if (i % 2 == 0) {
            for (int j = 0; j < W; j++) {
                vs[i][j] = t[j % 2];
            }
        }
        else {
            for (int j = 0; j < W; j++) {
                vs[i][j] = t[(j + 1)% 2];
            }
        }
    }
    for (int i = 0; i < H; i++) cout << vs[i] << endl;
    return 0;
}