str = input()
p = 0
if "pain" in str:
    idx = str.find("pain")
    str = str[:idx]
    lenS = len(str)
    i = 0
    while i < lenS:

        if str[i : i + 3] == "pon":
            p += 1
            i += 3
        else:
            i += 1
if p <= 1:
    print(-1)
else:
    print(p - 1)