#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    
    char Color[2] = { 'B','W' };
    int W,H;
    cin >> W >> H;
    string C;
    cin >> C;
    
    string S1,S2;
    for ( int i = 0; i < W; i++ ) {
        S1.push_back( Color[ ( C == "B" ) == ( i%2 ) ? 1 : 0 ] );
        S2.push_back( Color[ ( C == "B" ) == ( i%2 ) ? 0 : 1 ] );        
    }
    
    for ( int i = 0; i < H; i++ ) {
        cout << ( i%2 ? S2 : S1 ) << endl;
    }
    
    
    return 0;
}