// yukicoder: No.82 市松模様
// 2019.4.9 bal4u

#include <stdio.h>

char ch[3] = "BW";

int main()
{
	int W, H, r, c, c1, c0;
	char C[3];

	scanf("%d%d%s", &W, &H, C);
	c0 = (*C == 'W');
	for (r = 0; r < H; r++) {
		c1 = c0;
		for (c = 0; c < W; c++) putchar(ch[c1]), c1 = !c1;
		putchar('\n');
		c0 = !c0;
	}
	return 0;
}