#include <iostream>
using namespace std;

int main(){
    int w,h;
    char c,d;
    cin >> w >> h >> c;
    for(int i = 0; i < h; ++i){
        if(c=='B'){if(i%2!=0){d = 'W';}else{d='B';}}
        else if(c=='W'){if(i%2!=0){d = 'B';}else{d='W';}}
        for(int j = 0; j < w; ++j){
            if(d == 'B'){if(j%2==0){cout << "B";}else{cout << "W";}}
            else if(d == 'W'){if(j%2==0){cout << "W";}else{cout << "B";}}
        }
        cout << "\n";
    }
    return 0;
}