bright	operator
1	59.8	a
2	60	a
3	60.8	a
4	60.8	a
5	59.8	a
6	59.8	b
7	60.2	b
8	60.4	b
9	59.9	b
10	60	b
11	60.7	c
12	60.7	c
13	60.5	c
14	60.9	c
15	60.3	c
16	61	d
17	60.8	d
18	60.6	d
19	60.5	d
20	60.5	d