-- Exercice 1 --

P1 = (0,0)
P2 = (3,0)
S = [P1,P2]

|---------------------|
|  P2 = (5,0)         |
|  S = [(0,0);(5,0)]  |
|  lg = 5             |
|  P2 = (3,0)         |
|  S = [(0,0);(3,0)]  |
|  lg = 3             |
|                     |