s = input()
import sys
pon1 = 0
pon2 = 0
pain1 = 0
for i in s:
	if i == "pon"[pon2]:
		pon2 += 1
	else:
		pon2 = 0
		pon1 = 0
	if pon2 == 3:
		pon2 = 0
		pon1 += 1
	if i == "pain"[pain1]:
		pain1 += 1
	else:
		pain1 = 0
	if pain1 == 4:
		if pon1 == 0:
			print(-1)
		else:
			print(pon1)
		sys.exit()
print(-1)