import sys
readline=sys.stdin.readline
write=sys.stdout.write

S=readline().rstrip()
N=len(S)
for i in range(N-3):
    if S[i:i+4]=="pain":
        S=S[:i+4]
        cnt=S.count("pon")
        if cnt>=2:
            ans=cnt-1
        else:
            ans=-1
        break
else:
    ans=-1
print(ans)