#! ruby
# yukicoder My Practice
# author: Leonardone @ NEETSDKASU
############################################################
def gs() gets.chomp end
def gi() gets.to_i end
def gf() gets.to_f end
def gss() gs.split end
def gis() gss.map(&:to_i) end
def gfs() gss.map(&:to_f) end
def nmapf(n,f) n.times.map{ __send__ f } end
def ngs(n) nmapf n,:gs end
def ngi(n) nmapf n,:gi end
def ngss(n) nmapf n,:gss end
def ngis(n) nmapf n,:gis end
def arr2d(h,w,v=0) h.times.map{[v] * w} end
def for2p(hr,wr,&pr) hr.each{|i|wr.each{|j| yield(i,j)}} end
def nsum(n) n * (n + 1) / 2 end
def vcount(d,r=Hash.new(0)) d.inject(r){|r,e| r[e]+=1;r} end
############################################################

t = 0

f = arr2d(60,60)
x = 30
y = 30
dx = 1
dy = 0

UNKNOWN_CELL = 0
WALL_CELL = 1
SPACE_CELL = 2

f[y][x] = SPACE_CELL

def rot(dx, dy) [-dy, dx] end
def revrot(dx, dy) [dy, -dx] end

PERF = "FRBL"
def sk(f, x, y, dx, dy)
    a = [["X",99]]
    4.times do |i|
        tx, ty = x, y
        rx, ry = rot(dx, dy)
        lx, ly = revrot(dx, dy)
        loop {
            tx += dx
            ty += dy
            if f[ty][tx] == WALL_CELL
                break
            end
            if f[ty + ry][tx + rx] == UNKNOWN_CELL || f[ty + ly][tx + lx] == UNKNOWN_CELL
                a << [PERF[i], (tx - x).abs + (ty - y).abs]
                break
            end
        }
        dx, dy = rot(dx, dy)
    end
    a.min_by{|_,d|d}
end

loop {
    s = STDIN.gets
    break if s[0] == "M"
    if s.size > 2
        STDOUT.puts "F"
    else
        d = s.to_i
        nx = "X"
        if f[y + dy][x + dx] == UNKNOWN_CELL
            (1..d).each do |i|
                f[y + dy * i][x + dx * i] = SPACE_CELL
            end
            f[y + dy * d.succ][x + dx * d.succ] = WALL_CELL
        end
        nx, ny = rot(dx, dy)
        if f[y + ny][x + nx] == UNKNOWN_CELL
            nx = "R"
        else
            nx, ny = revrot(dx, dy)
            if f[y + ny][x + nx] == UNKNOWN_CELL
                nx = "L"
            else
                nx, ny = revrot(nx, ny)
                if f[y + ny][x + xy] == UNKNOWN_CELL
                    nx = "L"
                else
                    nx, _ = sk(f, x, y, dx, dy)
                    
                end
            end
        end
        case nx
        when "F"
            x += dx
            y += dy
        when "R"
            dx, dy = rot(dx, dy)
        when "L"
            dx, dy = revrot(dx, dy)
        when "B"
            x -= dx
            y -= dy
        else
            puts PREF[rand(4)]
        end
    end
    STDOUT.flush
}