#include <bits/stdc++.h>
#define REP(i,n) for(int i=0; i<(n); i++)
#define REP2(i,x,n) for(int i=x; i<(n); i++)
using namespace std;
int main(){
       
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int w, h;
    string c;
    cin >> w >> h >> c;
    
    REP( i, h ){
        REP( j, w ){
            if( c == "B" ){
                if( i%2 == 0 ){
                    cout << ( j%2 == 0 ? "B" : "W" );
                }else{
                    cout << ( j%2 != 0 ? "B" : "W" );
                }
            }else{
                if( i%2 != 0 ){
                    cout << ( j%2 == 0 ? "B" : "W" );
                }else{
                    cout << ( j%2 != 0 ? "B" : "W" );
                }
            }
        }
        cout << endl;
    }    
    return 0;
}