Problem: 

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 <image> 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

Solution (in PYTHON):

Solution:
## from matplotlib import pylab
## from math import sqrt
## 
## si = ["""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""", 
## """5
## 2.26 1.44
## 2.28 0.64
## 2.30 -0.30
## 1.58 0.66
## 3.24 0.66""", 
## """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""", 
## """5
## 10.44 2.06
## 10.90 0.80
## 11.48 -0.48
## 12.06 0.76
## 12.54 2.06""", 
## """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""", 
## """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"""]

## def p(s):
##     xy = []
##     for l in s.splitlines()[1:]:
##         x, y = map(float, l.split())
##         xy.append((x, y))
##     pylab.plot([x for x, y in xy], [y for x, y in xy])
##     return (5+sum([y for x, y in xy])/len(xy))

##print map(p, si)
##pylab.show()
n = int(raw_input())
sy = 0.0
for _ in range(n):
    x, y = map(float, raw_input().split())
    sy += y
print '%.3f' % (5 + sy/n)