#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int INF = 1e9;
int MOD = 1e9+7;
main(){
    int W,H;
    char C;
    cin >> W >> H >> C;
    char c[] = "BW";
    int next = (C=='W');
    for(int i = 0;i < H;i++){
        string s;
        for(int j = 0;j < W;j++){
            s += c[next];
            next = !next;
        }
        if(W % 2 == 0)next = !next;
        cout << s << endl;
    }
}