#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define chmin(x,y) x = min((x),(y));
#define chmax(x,y) x = max((x),(y));
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
const int INF = 1e9;
const long long LINF = 1e17;
const int MOD = 1000000007;
//const int MOD = 998244353;
const double PI = 3.14159265358979323846;

int main(){
    int w,h;
    char c;
    cin >> w >> h >> c;
    rep(i,h){
        rep(j,w){
            if((i+j)%2==0) cout << c;
            else cout << (c=='W'?'B':'W');
        }
        cout << endl;
    }
    return 0;
}