What country were both the 2015 and 2017 World Junior Ice Hockey Championships held?
2017 World Junior Ice Hockey Championships: The 2017 IIHF World Junior Championship was the 41st World Junior Ice Hockey Championships (WJC or WM20). 2017 World Junior Ice Hockey Championships:  The main tournament was co-hosted in Montreal, Quebec and Toronto, Ontario, in Canada. 2015 World Junior Ice Hockey Championships:  It was co-hosted by Toronto, Ontario and Montreal, Quebec, Canada, and organized by Hockey Canada, Hockey Quebec, the Ontario Hockey Federation, the Montreal Canadiens, Maple Leafs Sports and Entertainment and Evenko.
i don't know