#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#define CK(N, A, B) (A <= N && N < B)
#define REP(i, a, b) for (int i = a; i < b; i++)
#define RREP(i, a, b) for (int i = (b - 1); a <= i; i--)
#define F first
#define S second
#define ll long long

const int INF = 1e9;
const long long LLINF = 1e18;

using namespace std;

int dy[] = {0,1,0,-1};
int dx[] = {1,0,-1,0};
int dy8[] = {0,1,1,1,0,-1,-1,-1};
int dx8[] = {1,1,0,-1,-1,-1,0,1};

/*==================================================*/
/*variable*/
int W, H;
char C;
map<char, int> m = {{'W', 0}, {'B', 1}};
/*==================================================*/
/*function*/

/*==================================================*/

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

    REP(i,0,H){
        REP(j,0,W){

            if(i % 2 == 0){
                if((m[C] + j) % 2 == 0 ) cout<<"W";
                else cout<<"B";
            }else{
                if((m[C] + j) % 2 == 0 ) cout<<"B";
                else cout<<"W";
            }

        }
        cout<<endl;
    }

    return 0;
}