#include<cstdio>
#define rep(i,a) for(int i=0;i<(a);++i)

int main()
{
	int W, H;
	char C[2];

	scanf( "%d%d%s", &W, &H, C );

	rep( i, H )
	{
		rep( j, W )
			putchar( (i+j)&1?(*C=='B'?'W':'B'):*C );
		
		puts("");
	}

	return 0;
}