S=input()
pon="pon"
pain="pain"
memo=0
memo_pain=0
for i in range(len(S)-3):
    if S[i]!="p":
        pass
    elif S[i:i+4]==pain:
        memo_pain+=1
        break
    elif S[i:i+3]==pon:
        memo+=1
if memo_pain==1:
    if memo>=2:
        print(memo-1)
    else:
        print(-1)
else:
    print(-1)