s = io.read()
p = s:find("pain")
if not p then print(-1) os.exit() end
c = 0
a = 1
while true do
  a = s:find("pon", a)
  if a and a < p then
    c = c + 1
    a = a + 1
  else
    break
  end
end
print(2 <= c and c - 1 or -1)