import re
import sys

S = input()
if  "pain" not in S:
    print(-1)
    sys.exit()
S = S.split("pain")
# print(S)
results = re.findall(r"pon", S[0])
if len(results) >= 2:
    print(len(results)-1)
elif len(results) == 1:
    print(-1)
else:
    print(-1)