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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
const int Maxn = 1e8;
const int mod = 1e9 + 7;
namespace io {
const int _SIZE = (1 << 21) + 1;
char ibuf[_SIZE], *iS, *iT, c, stk[40];
int tot;
template <class I>
inline void read(I &_x) {
  I fl = 1;
  for (c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, _SIZE, stdin),
                       (iS == iT ? EOF : *iS++))
                     : *iS++);
       c < '0' || c > '9';
       c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, _SIZE, stdin),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    if (c == '-') fl = -1;
  for (_x = 0; c >= '0' && c <= '9';
       c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, _SIZE, stdin),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    _x = _x * 10 + (c & 15);
  _x *= fl;
}
template <class I>
inline void prt(I _x, char ch = '\0') {
  tot = 0;
  if (_x < 0) putchar('-'), _x *= -1;
  do {
    stk[tot++] = _x % 10 | 48;
    _x /= 10;
  } while (_x);
  do {
    putchar(stk[--tot]);
  } while (tot);
  if (ch) putchar(ch);
}
}  // namespace io
using io::prt;
using io::read;
inline int rd() {
  static int x;
  int f = 1;
  static char c;
  while ((c = getchar()) < '0' || c > '9')
    if (c == '-') f = -1;
  x = (c & 15);
  while ((c = getchar()) >= '0' && c <= '9') x = (x << 3) + (x << 1) + (c & 15);
  return x * f;
}
int n;
float ans, x, y;
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%f%f", &x, &y);
    ans += y;
  }
  ans = ans / n + 5.0;
  printf("%.3f", ans);
  return 0;
}