#include <iostream>
using namespace std;

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

    char ans[50][50];
    for(int i = 1; i <= h; i++){
        for(int j = 1; j <= w; j++){
            if((i + j) % 2 == 0) 
                ans[i][j] = c;
            else
                ans[i][j] = ((c == 'B') ? 'W' : 'B');
                
            cout << ans[i][j];
        }
        cout << endl;
    }

    return 0;
}