milieu	N
A	0
A	1
A	1
A	1
A	1
A	1
A	2
A	2
A	2
A	2
A	2
A	2
A	4
A	4
A	4
B	7
B	7
B	8
B	9
B	9
B	10
B	10
B	10
B	11
B	12
B	13
B	14
B	15
B	16
B	16