I am looking for a French movie (probably mid 80’s) about two groups of schoolboys fighting each other, very similar to “War of the Buttons”, but not that movie. It is probably set in the 30’s, all the boys wear black capes. The movie is told from the point of view of one of them, named Francois, his opponent’s name is Augustin. That boy wanted to betray the group, but they found out, beat him and pulled his pants down. At one point one of them is punished at school – the teachers make him stand on his knees on a bench. The second part of the movie describes their adventures, when they are 17 years old and go to a concert in the opera, later they discuss it in class.