s = input()

if "pain" not in s:
    print(-1)
else:
    for i in range(len(s)):
        if s[i:i+4] == "pain":
            j = i
            break

    t = s[:j]
    cnt = 0
    for i in range(len(t)):
        if t[i:i+3] == "pon":
            cnt += 1
    if cnt < 2:
        print(-1)
    elif cnt >= 2:
        print(cnt - 1)