http://edition.cnn.com/2016/07/15/sport/favela-rugby-brazil-olympics-sevens/index.html
When developing countries are trying to prepare for Olympics, many countries are concerned about(actually scorn) delayed preparation or local safety. We should take for granted that those countries won't be able to hold Olympics satisfactorily.
But, through preparation for Olympics, host countries can improve its economy. For example, construction plan of the stadium in favela(Shanty town) is a chance for improving city landscapes and it's also chance for people in poverty to get a new houses given by a government.
I hope Olympics plays a role not only as a symbol of global peace but also as a drivingforce of economic growth for host countries.
