Since the first park was built in Shanghai in 1868, there have been nearly 140 parks so far. Among them, there are 19 paid parks, and 8 free parks are 6 times more than the paid parks. How many free parks are there in Shanghai?
上海从1868年建造了第一个公园起，至今已有近140个公园．其中收费公园有19个，免费公园比收费公园的6倍多8个，上海免费公园有多少个？
<result>121</result>