#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv) {
	union {
		short s;
		char c[sizeof(short)];
        } un;

	un.s = 0x0102;
	if (sizeof (short) == 2) {
		if (un.c [0] == 1 && un.c [1] == 2) {
			printf("B\n");
                } else {
			if (un.c [0] == 2 && un.c [1] == 1) {
				printf("L\n");
			}
		}
	} else {
		printf("?\n");
	}
	return (EXIT_SUCCESS);
}