def main():
    s = input()
    if s.find("pain") == -1:
        print(-1)
        exit()
    cnt = 0
    while True:
        if s[0:4] == "pain":
            break
        
        if s[0:3] == "pon":
            s = s[3:]
            cnt += 1
        else:
            s = s[1:]
        
    result = -1 if cnt < 2 else cnt-1
    print(result)


if __name__ == "__main__":
    main()