$|=1;
sub i{$_=<>;/M/&&exit;$_+0}
sub o{print"@_\n"}
while(1){
	$d=$d+1&3,o L while!i;
	$x1=$x+(1,0,-1,0)[$d];
	$y1=$y+(0,1,0,-1)[$d];
	if($m{$x1,$y1}==0||$m{$x1,$y1}==($d^6)){
		$m{$x,$y}=$d^4;
		$x=$x1;$y=$y1;o F;i;
		$d=$d-1&3,o R;
	}else{
		$d=$d+1&3,o L;
	}
}