//No.82 市松模様
#pragma GCC optimize("O3")
#pragma GCC target("avx")
#include <bits/stdc++.h>
#define rep(i ,n) for(int i=0;i<(int)(n);++i)
#define repr(i ,n) for(int i=n;i>(int)(n);--i)
#define rep1(i ,n) for(int i=1;i<=(int)(n);++i)
#define ALL(a) a.begin(), a.end()
#define RSORT(a) sort(ALL(a),greater<>())
#define SORT(a) sort(ALL(a))
#define bit_check(bit, i) ((bit>>(i)) & 1)
#define PRINT(x) cout << (x) << endl;
#define ENDL cout << endl;
using namespace std;
typedef long long int i64;
typedef unsigned long long u64;
template<class T> using V = vector<T>;
using VI = V<int>;
const int INF = 2e9;
const i64 MOD = 1e9 + 7;

template <class T> inline bool chmin(T& a, T b){if(a>b){a=b; return true;} return false;}
template <class T> inline bool chmax(T& a, T b){if(a<b){a=b; return true;} return false;}
struct Init_On{
    Init_On(){
        cin.tie(nullptr);
        ios_base::sync_with_stdio(false);
        cout << fixed << setprecision(16);
    }
};

signed main(){
    int w , h;
    char c1 , c2; cin >> w >> h >> c1;
    if( c1 == 'W') c2 = 'B';
    else c2 ='W';
    bool b = true;
    rep( i , h){
        if(!b) {b = true;c1^=c2; c2^=c1; c1^=c2;}
        else if ( i != 0 && b) {b = false; c1^=c2; c2^=c1; c1^=c2;}
        rep( j , w){  
            if(j % 2 == 0){
                cout << c1;
            } else { 
                cout << c2;
            }
        }
        cout << endl;
    }
}