#include <cstdio>
#include <iostream>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <string>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <functional>
#include <queue>
#include <stack>
#include <cmath>
#include <iomanip>
#include <list>
#include <tuple>
#include <bitset>
#include <ciso646>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;

inline bool cheak(ll x, ll y, ll xMax, ll yMax){ return x >= 0 && y >= 0 && xMax > x && yMax > y; }
inline ll toInt(string s) { ll v; istringstream sin(s); sin >> v; return v; }
template<class T> inline string toString(T x) { ostringstream sout; sout << x; return sout.str(); }
template<class T> inline T sqr(T x) { return x*x; }

#define For(i,a,b)	for(ll (i) = (a);i < (b);(i)++)
#define rep(i,n)	For(i,0,n)
#define rFor(i,a,b)	for(ll (i) = (a-1);i >= (b);(i)--)
#define rrep(i,n)	rFor(i,n,0)
#define clr(a)		memset((a), 0 ,sizeof(a))
#define mclr(a)		memset((a), -1 ,sizeof(a))
#define all(a)		(a).begin(),(a).end()
#define sz(a)		(sizeof(a))

const int dx[8] = { 1, 0, -1, 0, 1, 1, -1, -1 }, dy[8] = { 0, -1, 0, 1, -1, 1, -1, 1 };
const ll mod = 1e9 + 7;
const ll INF = 1e9 + 2;

int n;
vector<ll> v;

int main(){
	int w, h;
	char c;
	cin >> w >> h >> c;

	rep(y, h){
		string s;
		if (y % 2 == 0)
		rep(x, w){
			if (x % 2){
				if (c == 'W')s += "B";
				else s += 'W';
			}
			else{
				if (c == 'W')s += "W";
				else s += 'B';
			}
		}
		else
		rep(x, w){
			if (x % 2){
				if (c == 'W')s += "W";
				else s += 'B';
			}
			else{
				if (c == 'W')s += "B";
				else s += 'W';
			}
		}
		cout << s << endl;
	}



	return 0;
}