#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < n; i++) //[0,n)
#define srep(i,a,b) for(int i = a; i < b; i++) //[a,b)
#define all(A) (A).begin(),(A).end()
#define rall(A) (A).rbegin(),(A).rend()
#define pmt(A) next_permutation(A)
using namespace std;
using ll = long long;
using ull = unsigned long long;
using P = pair<ll,ll>;
using pq = priority_queue<ll,vector<ll>,greater<ll>>;
const ll inf = 8e18;
const int iinf = (int)1e9;
const int mod9 = 998244353;
const int mod1 = 1000000007;
struct Edge { int to; ll cost; int from; };
bool compe(const Edge &e,const Edge &e2){ return e.cost < e2.cost; }
using Graph = vector<vector<int>>;
using EGraph = vector<Edge>;
using SGraph = vector<set<ll>>;
template <typename T>
int siz(T& a){ return (int)a.size(); }
ll squa(ll a){ return a*a; }
int ceil(int a,int b){ return (a+b-1)/b; }
using namespace std;

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