word = input()
pon = -1
pain = 0
for i in range(len(word)-3):
	if word[i:i+3] == "pon":
		pon += 1
	if word[i:i+4] == "pain":
		pain = 1
		break

if pon < 1 or pain == 0:
	print(-1)
else:
	print(pon)