n = io.read("*n", "*l")
s = io.read()
t = {}
for i = 2, n do
  if s:sub(i, i) == "o" and s:sub(i - 1, i - 1) == "x" then
    table.insert(t, i)
  end
end
print(#t)
print(table.concat(t, " "))