#D2660. On a plane
On a plane
On a plane
Input
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 xi and yi 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
inputFormat
Input
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 xi and yi of the point, specified with exactly 2 fractional digits. All coordinates are between - 1000 and 1000, inclusive.
outputFormat
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
样例
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
6.040