X=[
  [ [ 1, 1, 2, 0], [ 0, 1, 3, 2], [ 0, 0, 1, 1], [ 0, 0, 3, 4], [ 1, 0, 1, 3] ],
  [ [ 0, 0, 3, 0], [ 0, 0, 0, 2], [ 0, 1, 2, 1], [-1, 0, 0, 4], [ 0, 0, 2, 3] ],
  [ [-1,-1, 0, 0], [ 0,-1, 1, 2], [ 0, 0, 3, 1], [ 0, 0, 1, 4], [-1, 0, 3, 3] ],
  [ [ 0, 0, 1, 0], [ 0, 0, 2, 2], [ 0,-1, 0, 1], [ 1, 0, 2, 4], [ 0, 0, 0, 3] ],
]
def solve(input)
  axis=[0,0]
  pos=dir=0
  memo={[*axis,pos]=>0}
  input.scan(/[ac]*F/).each_with_index{|m,i|
    dir=(dir+(m.size-1)*(?b<=>m[0]))%5
    dx,dy,pos,dir=X[pos][dir]
    axis[0]+=dx
    axis[1]+=dy
    t=memo[[*axis,pos]] and return [i+1,t]*?,
    memo[[*axis,pos]]=i+1
  }
  ?-
end
def test(n,input,expected)
  actual=solve(input)
  puts "case #{n}: " + ( actual==expected ? "ok" : "ng ( #{actual} against #{expected} )" )
end
test(0, "FcFcFaF", "3,0" )
test(1, "FccFaaFcFcF", "-" )
test(2, "ccFaF", "-" )
test(3, "cFcFaaF", "-" )
test(4, "aFccFcFcF", "4,1" )
test(5, "cFaFaFaFaaF", "4,0" )
test(6, "cFccFaFaaFaF", "5,1" )
test(7, "cFaaFaaFcFcFccF", "5,2" )
test(8, "aaFaFaaFaFccFaFccF", "6,0" )
test(9, "aaFaaFcFccFcFccFccFaF", "6,1" )
test(10, "aFccFccFaaFccFcFcFcFaF", "7,4" )
test(11, "ccFaaFaaFaFccFaaFaFcFccFaaF", "-" )
test(12, "aaFaFaFcFaFaaFaFaFaaFccFaaFaaF", "8,3" )
test(13, "aaFccFaFaFccFaaFaaFaaFccFccFcFaFaF", "13,10" )
test(14, "aFaFaaFaaFaaFccFaFccFaFaaFccFccFaaFccF", "11,0" )
test(15, "ccFccFcFaaFaaFaFccFaaFaFcFaaFaaFcFcFcF", "10,2" )
test(16, "aaFaaFaaFccFccFaFaaFaaFaFccFcFcFccFaaFaFccFccF", "10,3" )
test(17, "ccFaFccFaaFaaFcFccFaFcFccFccFaaFccFaFaaFaFaFccF", "11,3" )
test(18, "cFcFaFaaFaFccFaaFcFaFaaFccFaFaaFccFaFcFaaFccFcF", "12,0" )
test(19, "cFaFaaFcFaaFaaFaFccFaaFcFaaFccFaaFccFaFcFccFaFaFaFcFcF", "19,16" )
test(20, "aFaFccFaaFccFccFaFccFaFaaFccFaaFccFcFccFaFaFccFaaFccFcF", "15,11" )
test(21, "aFccFccFccFaaFaaFcFcFaaFccFaFcFccFaaFaFcFaaFcFaFccFccFaFaF", "23,20" )
test(22, "cFaFaaFcFaFaaFccFccFaaFaFccFccFccFaFaFccFccFccFaaFcFcFcFaF", "22,18" )
test(23, "aFcFaFccFccFaFccFaaFaFaaFaaFaFcFaFcFcFcFaFaFaaFaaFaFaaFcFccFaF", "14,4" )
test(24, "cFaFaaFcFaFccFcFccFaFaaFaaFaFcFccFccFaFcFaFaaFccFaFaFccFcFaFaFaaF", "22,19" )
test(25, "aaFaaFaFcFccFaaFcFaaFccFaFaFcFaFaaFaFaFaFcFccFaFaaFcFcFccFccFccFcF", "16,11" )
test(26, "cFaaFaFcFaFaaFccFaaFaFccFccFaaFccFcFaFaaFaaFaFccFcFccFccFaFaaFcFcFaF", "26,23" )
test(27, "cFaaFccFaFcFaFcFaaFccFaFccFaaFcFaFaaFccFaaFccFcFaFaaFaFcFccFccFaFcFaaFccFcF", "-" )
test(28, "ccFccFaaFaFccFaaFaaFcFccFaaFaFcFccFccFccFaFaaFcFaFccFaaFcFcFaFccFaFccFaaFaaFaF", "-" )
test(29, "aaFccFaFccFccFaaFccFaFcFccFaFccFcFcFaFcFcFaaFaaFcFccFccFcFaFaaFaFcFcFaaFaaFaaF", "19,5" )
test(30, "aFaaFccFaFaaFaaFccFccFaFcFaaFaaFaaFccFaFccFaaFaaFaFccFccFcFaaFaFccFccFaFcFaaFccF", "-" )
test(31, "aaFaFaaFcFccFccFaFcFaaFaaFaFccFccFccFaFaaFccFcFaaFccFaaFccFaaFccFccFccFcFaaFcFaaFccF", "30,23" )
test(32, "aaFccFaFaaFccFcFaFccFaFcFccFaaFccFaFcFaaFccFaaFaFccFccFccFcFccFaFccFcFaaFaFcFccFcFaFaaF", "32,17" )
test(33, "ccFcFcFaFaaFaFaaFccFcFccFaFcFaFccFaaFcFccFcFaaFcFaaFcFaaFaaFcFaaFaFaFaFaaFccFaaFcFcFaFaF", "18,14" )
test(34, "ccFaFaaFaaFcFaaFaaFaaFaaFaaFaFccFcFaaFaFcFccFaaFcFaFaaFccFccFaaFcFaaFaaFaaFccFaaFcFcFaFaFccFaFcFccF", "17,0" )
test(35, "aaFccFccFaFcFaFcFaFccFccFccFaFccFccFcFaFcFaaFccFcFccFccFaaFcFccFaaFccFccFaFccFcFcFaaFaFccFcFaaFaaFcF", "24,11" )
test(36, "aaFccFaFccFaaFaaFcFaFcFaFcFaaFaaFccFaFcFaFaaFcFaaFaFcFaaFccFcFaaFccFaaFccFaaFccFcFaFcFaFccFaaFaaFccFaaF", "-" )
test(37, "aFaaFaFaaFcFccFaaFccFaFcFaaFccFccFcFcFaFaFcFccFcFccFaaFcFaFcFaaFcFaFaaFccFaaFccFaFaaFaFcFaFccFaFaaFaFaaF", "17,14" )
test(38, "aaFcFaaFccFaaFaaFcFaaFccFccFaFcFaFcFccFcFaaFaaFaFcFaFcFaaFcFaFaaFaFccFccFccFcFaFaFcFcFaFcFaaFcFaaFcFcFaaF", "27,23" )
test(39, "ccFaFccFaFcFaFccFcFaaFccFccFcFaFccFccFaaFaaFaFaaFcFaaFccFcFaaFcFccFaaFcFaFccFccFaFccFaaFaaFcFcFccFaFccFcFcF", "25,18" )
test(40, "cFcFccFaFaaFaaFccFccFcFccFccFaFcFaaFcFccFccFcFccFaFaFaFaFaFaaFaFcFaFccFcFccFaaFccFaaFccFcFaFaaFccFaFccFcFaaF", "16,4" )
test(41, "aFcFcFaaFcFaaFcFaFaaFaaFaaFaFcFccFccFccFaFaaFaFaaFaaFcFcFccFaFaaFcFaFaaFccFaaFcFccFcFcFccFaaFcFaFccFaaFaaFccF", "19,15" )
test(42, "ccFaaFcFaFccFaFccFaFcFaaFaaFccFaaFccFcFaFaFccFaFaaFaFaaFaFaaFaaFccFaaFaFcFaaFaFaFcFaaFcFaFaaFaaFcFccFaaFaFaFaF", "22,17" )
test(43, "aaFcFaaFaFcFccFccFaFaFccFaFaaFaFcFccFaaFaaFaaFcFccFccFaFaaFccFcFaFaFcFaaFcFcFcFccFccFaaFcFcFaFccFccFccFaaFcFaaFcF", "14,5" )
test(44, "cFcFaFccFaaFaFccFaFccFaaFaFccFaaFaaFccFaaFccFaaFccFaFaaFaFaFaaFaaFccFaFcFaaFcFcFaFaFcFcFcFaFaaFcFaFcFaaFccFccFcFaaFaFccF", "10,1" )
test(45, "ccFaFcFaaFcFccFaFccFaaFccFaaFaaFcFaaFccFaaFccFccFcFaaFaaFcFaaFccFaaFcFcFaaFaFaFccFcFaFaFaFccFccFccFccFccFccFcFcFccFccFcF", "25,13" )
test(46, "aFccFaFcFaFcFaaFaaFcFaaFccFaFaaFaFcFaFaaFaaFaaFccFaaFaaFccFccFccFccFccFaaFaFcFaFaFccFaFccFcFccFcFcFccFcFccFccFccFccFccFaF", "18,8" )
test(47, "cFaaFcFaaFaFcFccFaaFcFccFcFaFccFaaFaaFccFccFccFaFcFccFcFaaFcFcFccFcFccFaFaFccFccFcFaFaFaaFcFaFcFccFccFccFaaFaFaFccFcFccFccF", "25,22" )
test(48, "aaFcFccFcFaFcFaFaFcFccFaFaaFaFcFccFccFaaFccFccFaaFaaFccFaaFaaFccFaaFccFcFaaFaFcFaFcFccFaaFccFaFaFccFaaFcFaaFaFccFaaFaaFccFccFcFaF", "-" )
test(49, "aFaaFccFccFaaFaaFccFccFaaFaaFaFcFccFaFcFaaFaFccFaaFccFaFcFaFccFaaFaaFaFccFaFaaFaaFcFaaFccFaaFcFaFccFccFaaFaaFaaFaaFccFcFccFaaFaFaaFaaF", "-" )
test(50, "aaFcFccFccFaFccFaFccFaaFaaFaaFccFaaFaaFccFaaFccFaFaaFccFccFaaFcFccFaFccFcFaaFaFccFccFccFaaFaFccFccFaFaaFccFccFccFaaFccFccFaFaFcFaFccFccF", "-" )