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


if __name__ == "__main__":
    main()