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 JAVA):

Solution:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;

public class Task409G {

    public static void main(String... args) throws NumberFormatException,
            IOException {
        Solution.main(System.in, System.out);
    }

    static class Scanner {

        private final BufferedReader br;
        private String[] cache;
        private int cacheIndex;

        Scanner(InputStream is) {
            br = new BufferedReader(new InputStreamReader(is));
            cache = new String[0];
            cacheIndex = 0;
        }

        int nextInt() throws IOException {
            if (cacheIndex >= cache.length) {
                cache = br.readLine().split(" ");
                cacheIndex = 0;
            }
            return Integer.parseInt(cache[cacheIndex++]);
        }

        int nextInt(int radix) throws IOException {
            if (cacheIndex >= cache.length) {
                cache = br.readLine().split(" ");
                cacheIndex = 0;
            }
            return Integer.parseInt(cache[cacheIndex++], radix);
        }

        long nextLong() throws IOException {
            if (cacheIndex >= cache.length) {
                cache = br.readLine().split(" ");
                cacheIndex = 0;
            }
            return Long.parseLong(cache[cacheIndex++]);
        }

        double nextDouble() throws IOException {
            if (cacheIndex >= cache.length) {
                cache = br.readLine().split(" ");
                cacheIndex = 0;
            }
            return Double.parseDouble(cache[cacheIndex++]);
        }

        String next() throws IOException {
            if (cacheIndex >= cache.length) {
                cache = br.readLine().split(" ");
                cacheIndex = 0;
            }
            return cache[cacheIndex++];
        }

        void close() throws IOException {
            br.close();
        }

    }

    static class Solution {

        public static void main(InputStream is, OutputStream os)
                throws NumberFormatException, IOException {
            PrintWriter pw = new PrintWriter(os);
            Scanner sc = new Scanner(is);

            int n = sc.nextInt();

            double sumY = 0;
            for(int i = 0 ; i < n ; i++){
                sc.nextDouble();
                sumY += sc.nextDouble();
            }

            pw.println(5.0 + sumY/n);

            pw.flush();
            sc.close();
        }
    }

}