#include"bits/stdc++.h"
using namespace std;
using ll=long long;
using ull=unsigned long long;
using ld=long double;
#define all(a)a.begin(),a.end()
#define rall(a)a.rbegin(),a.rend()
#define rep(i,n)for(int i=0;i<(n);++i)
#define YN(ans)cout<<(ans?"Yes\n":"No\n")
#define uni(a)sort(all(a)),a.erase(unique(all(a)),a.end())
#define pv(a)cerr<<#a<<':';for(auto e:a)cerr<<' '<<e;cerr<<'\n'
#define mine(a)*ranges::min_element(a)
#define maxe(a)*ranges::max_element(a)
#define sume(a)accumulate(all(a),0LL)
template<class T>bool chmin(T&a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
constexpr int inf=2e9,dx4[4]={0,-1,0,1},dy4[4]={1,0,-1,0},dx8[8]={0,-1,-1,-1,0,1,1,1},dy8[8]={1,1,0,-1,-1,-1,0,1};
constexpr ll INF=2e18;

int main(){
    cin.tie(0)->sync_with_stdio(0);
    cout<<fixed<<setprecision(0);
    ll W,H;cin>>W>>H;
    char C;cin>>C;
    rep(i,H){
        rep(j,W)cout<<(((i+j)%2==0)^(C=='B')?'W':'B');
        cout<<'\n';
    }
}