def main():
    S = input()
    target = 'pain'
    idx = S.find(target)

    if idx == -1:
        print(idx)
    else:
        r = S[:idx]
        pains = r.count('pon') - 1
        if pains > 1:
            print(pains)
        else:
            print('-1')

if __name__ == '__main__':
    main()