Description

Mr.Skywind received a gift – a mysterious telescope. The telescope can report accurate distance of stars. But Skywind want to know the average distance of these stars that the mysterious telescope can not display. On the other hand, the accurate number is too long to read, so Skywind need a brief form.

Input

The first line of each case is the number of stars N(0<N<100), N=0 means the end of input. The next N lines are distance of each star. The distance may be integer or real number which can be expressed in double type.

Output

For each test case, output the average distance in one line. The output should use fixed notation which accurate to 4 decimal places. See the detail format from sample.

Sample

Input

4
1.0
200
320.2
4.32
1
0.001
0

Output

131.3800
0.0010

Source: qn