人間の鎖
The Nordic Mathematical Contest (NMC) is a mathematics competition for secondary school students from the five Nordic countries: Denmark, Finland, Iceland, Norway and Sweden. It takes place every year in March or April and serves the double purpose of being a regional secondary school level mathematics competition for the Nordic region and a step in the process of selection of the teams of the participating countries for the International Mathematical Olympiad (IMO) and the regional Baltic Way competition.