integer idM, idF
function F(integer n)
if n = 0 then
return 1
else
return n - call_func(idM,{F(n-1)})
end if
end function
idF = routine_id("F")
function M(integer n)
return 0
return n - call_func(idF,{M(n-1)})
idM = routine_id("M")