railway has 10 stations in total. If only one type of ticket is used from each starting station to the terminal station (at least 5 stations are separated in the middle), how many types of such tickets are there in total?
一条铁路，共有10个车站，如果每个起点站到终点站只用一种车票(中间至少相隔5个车站)，这样的车票共有多少种．
<result>30</result>