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G. On a plane

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputInput

The first line contains a single integer *n* (1 ≤ *n* ≤ 1000) — the number of points on a plane.

Each of the next *n* lines contains two real coordinates *x*_{i} and *y*_{i} of the point, specified with exactly 2 fractional digits. All coordinates are between - 1000 and 1000, inclusive.

Output

Output a single real number θ — the answer to the problem statement. The absolute or relative error of your answer should be at most 10^{ - 2}.

Examples

Input

8

-2.14 2.06

-1.14 2.04

-2.16 1.46

-2.14 0.70

-1.42 0.40

-0.94 -0.48

-1.42 -1.28

-2.16 -1.62

Output

5.410

Input

5

2.26 1.44

2.28 0.64

2.30 -0.30

1.58 0.66

3.24 0.66

Output

5.620

Input

8

6.98 2.06

6.40 1.12

5.98 0.24

5.54 -0.60

7.16 0.30

7.82 1.24

8.34 0.24

8.74 -0.76

Output

5.480

Input

5

10.44 2.06

10.90 0.80

11.48 -0.48

12.06 0.76

12.54 2.06

Output

6.040

Input

8

16.94 2.42

15.72 2.38

14.82 1.58

14.88 0.50

15.76 -0.16

16.86 -0.20

17.00 0.88

16.40 0.92

Output

6.040

Input

7

20.62 3.00

21.06 2.28

21.56 1.36

21.66 0.56

21.64 -0.52

22.14 2.32

22.62 3.04

Output

6.720

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